This glossary is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Monterey Institute of International Studies.


  • Abolition 2000

    Founded in 1995 during the NPT Review and Extension Conference, Abolition 2000 is an international non-governmental global network working for a treaty to eliminate nuclear weapons within a time-bound framework. The coalition consists of over 2,000 organizations from 90 different countries that work both independently and in concert to accomplish the goal of nuclear abolition through an eleven point program.

  • Acheson-Lilienthal Proposal

    A U.S. initiative to outlaw nuclear weapons and to internationalize global stocks of fissile material for use in peaceful nuclear programs which became know as the Baruch Plan. See entry for Baruch Plan.

  • Active Defenses

    Active defenses use weapon systems or countermeasures to defend against an attack. See entry for Passive Defenses

  • Adamsite


    A chemical agent that causes eye, nose, and respiratory tract irritation in addition to vomiting and diarrhea.  Classified as a vomiting agent, adamsite is odorless and usually enters the body by inhalation. Upon entering the body, adamsite poisoning begins within minutes and lasts up to several hours.  First synthesized in 1918, adamsite was used by the Japanese during World War II.  While some have stockpiled adamsite as a riot-control agent, the OPCW Scientific Advisory Board recommends against such use. 

  • Additional Protocol

    The Additional Protocol is a legal document granting the International Atomic Energy Agency (IAEA) complementary inspection authority to that provided in underlying safeguards agreements. The principal aim is to enable the IAEA inspectorate to provide assurance about both declared and possible undeclared activities. Under the Protocol, the IAEA is granted expanded rights of access to information and sites, as well as additional authority to use the most advanced technologies during the verification process. See entry for Information Circular 540.

  • Ad Hoc Group of Governmental Experts to Identify and Examine Potential Verification Measures from a Scientific and Technical Standpoint

    Created in September 1991 during the Third Review Conference of the Biological and Toxin Weapons Convention (BTWC), VEREX was tasked with identifying measures that could be used to determine whether a state party to the BTWC is “developing, producing, stockpiling, acquiring, or retaining” biological weapons (BW). In its final report of September 24, 1993, VEREX described and analyzed 21 such measures, including but not limited to declarations of biological agents, on-site inspections, and multilateral information sharing.

  • Advanced Cruise Missile (ACM)

    See entry for Cruise missile.

  • Aegis

  • Aerosol

    A system of liquid or solid particles uniformly distributed in a finely divided state through a gas, usually air.  Because aerosols are a means for delivering chemical and biological agents, they can play an important role in weaponizing these substances.

  • African Nuclear-Weapon-Free-Zone

    The Treaty on the African Nuclear-Weapon-Free-Zone, also known as the Treaty of Pelindaba, was opened for signature in Cairo in April 1996. The treaty prohibits the research, development, manufacturing, stockpiling, acquisition, testing, possession, control, and stationing of nuclear explosive devices on any member’s territory. The treaty also prohibits the dumping of radioactive waste originating from outside the continent within the region. In addition, the treaty requires parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities. The treaty also provides for the establishment of the African Commission on Nuclear Energy (AFCONE), which supervises treaty implementation and ensures compliance with its provisions.

  • Agreed Framework

    The 1994 agreement between the United States and North Korea (Democratic People’s Republic of Korea, DPRK) to “freeze” the DPRK’s nuclear program. The agreement outlined a 10-year program during which the United States, South Korea, and Japan would construct two new light-water-moderated nuclear reactors in the DPRK in exchange for the shutting down of all of the DPRK’s existing nuclear facilities. In addition, the DPRK agreed to remain a party to the NPT and to accept IAEA full-scope safeguards. The multilateral Korean Peninsula Energy Development Organization (KEDO) would oversee implementation of the agreement.

    See glossary entries for Joint Declaration on the Denuclearization of the Korean Peninsula, Korean Peninsula Energy Development Organization.

  • Agreement Governing the Activities of States on the Moon

    An agreement supplementing the Outer Space Treaty, and confirming the demilitarization of the Moon and other celestial bodies. Activities on the moon are limited to peaceful purposes. The Moon agreement was opened for signature on December 18, 1979, and entered into force on July 11, 1984.

  • Air Defenses

    Weapon systems deployed to defend territory or troops from attack by aircraft, cruise or ballistic missiles. Air defense weapons include air, land and sea-based radar guided or infrared homing surface-to-air or air-to-air missiles, and automatic gunfire.

  • Air Independent Propulsion Technology (AIP)

    A propulsion system that uses liquid (or compressed) oxygen or hydrogen fuel cells, thereby allowing submarines to stay submerged for longer periods without the need for external sources of oxygen. This increased endurance also increases a submarine’s survivability.

  • Air-Launched Cruise Missile (ALCM)

    A missile designed to be launched from an aircraft and jet-engine powered throughout its flight. As with all cruise missiles, its range is a function of payload, propulsion, and fuel volume, and can thus vary greatly. Under the START I Treaty, the term “long-range ALCM” means an air-launched cruise missile with a range in excess of 600 kilometers.

  • Alpha particle

    A positively charged particle ejected spontaneously from the nuclei of some radioactive isotopes. It is a helium nucleus that has a mass number of 4 and an electrostatic charge of +2e. It has low penetrating power and a short range (a few centimeters in air). The most energetic alpha particle will generally fail to penetrate the dead layers of cells covering the skin and can be easily stopped by a sheet of paper. Alpha particles are hazardous when an alpha-emitting isotope is inside the body.

  • Al-Qaeda or Al-Qa’ida

    A radical Islamist terrorist organization established by Osama bin Laden (now deceased), responsible for a number of attacks in the United States and worldwide, including the September 11, 2001 attacks on the World Trade Center and Pentagon. Al-Qa’ida means “the base” in Arabic, and acts as an umbrella organization for a number of terrorist groups around the world. The organization’s current leader is Ayman al-Zawahiri.

  • Antarctic Treaty

    The Antarctic Treaty was opened for signature on December 1, 1959, and entered into force on June 23, 1961. The Antarctic Treaty internationalizes and demilitarizes the Antarctic continent. It specifies that Antarctica be used for peaceful purposes only; all activities of a military nature, including testing of any type of weapon, are prohibited. No military activities, armaments, or prohibited nuclear activities have been observed on the continent during inspections by member states since the treaty went into force.

  • Anthrax

    The common name of the bacterium Bacillus anthracis, as well as the name of the disease it produces.  A predominantly animal disease, anthrax can also infect humans and cause death within days.  B. anthracis bacteria can form hardy spores, making them relatively easy to disseminate.  Germany, the United Kingdom, the United States, and the USSR/Russia have all investigated anthrax as a biological weapon, as did the Japanese cult Aum Shinrikyo.  Anthrax-laced letters were also used to attack the U.S. Senate and numerous news agencies in September 2001.  There is no vaccine available to the general public, and treatment requires aggressive administration of antibiotics.

  • Anthrax Attacks

    Refers to the 2001 mailing of a total of seven letters containing anthrax to several U.S. news outlets and the offices of two U.S. senators. These attacks killed five and sickened 17. The investigation of the attacks by an FBI-led task force is known as Amerithrax.

  • Anti-Ballistic Missile (ABM) Treaty

    The Anti-Ballistic Missile (ABM) Treaty, which was signed by the United States and the Soviet Union on May 26, 1972, and entered into force on October 3, 1972, constrained strategic missile defenses to a total of 200 launchers and interceptors per country, which were divided between two widely separated deployment areas. These restrictions were intended to prevent the establishment of a nationwide defense, and the creation of a base for deploying such a defense. The treaty was modified in 1974, reducing the permitted deployment areas to one per country. The United States withdrew from the ABM Treaty in 2002.

  • Anti-Satellite Weapon (ASAT)

    A system designed to destroy or disable enemy satellites in orbit.

  • Arms control

    Measures, typically bilateral or multilateral, taken to control or reduce weapon systems or armed forces. Such limitations or reductions are typically taken to increase stability between countries, reducing the likelihood or intensity of an arms race.  They might affect the size, type, configuration, production, or performance characteristics of a weapon system, or the size, organization, equipment, deployment, or employment of armed forces. Arms control measures typically include monitoring and verification provisions, and may also include provisions to increase transparency between the parties. Also see entry for Confidence and Security Building Measures, Transparency Measures.

  • Arms Control and Regional Security in the Middle East (ACRS)

    The Madrid Peace Conference in October 1991 established a multilateral working group on Arms Control and Regional Security. The ACRS working group, along with four other multilateral working groups, was created to complement bilateral negotiations between Israel and its immediate neighbors. Since 1992, 13 Arab states, Israel, a Palestinian delegation, and a number of extra-regional entities have participated in plenary and intercessional meetings. However, the lack of universal membership in the region (neither Iran nor Iraq is a party to the ACRS), and complications in the peace process have hindered progress. The agreed measures have not been implemented, and the ACRS has not held a formal plenary meeting since September 1995.

  • Association of Southeast Asian Nations (ASEAN)

    The Association of South East Asian Nations (ASEAN) is a regional organization established on August 8, 1967, whose objectives include the acceleration of economic growth and the promotion of regional peace and stability in Southeast Asia. It was established by five original member countries, but now consists of ten members and two observers. Among other achievements, ASEAN was responsible for the establishment of a nuclear-weapon-free zone in Southeast Asia, created by the Treaty of Bangkok at the Fifth ASEAN Summit in 1995.

  • Atom

    The smallest unit of an element which cannot be divided or broken up by chemical means, and has all the chemical properties of that element. It consists of a central core of protons and neutrons, called the nucleus. In atomic models, electrons revolve in orbits around the nucleus. Atoms are the fundamental building blocks of elements.

  • Atomic

    Pertaining to an atom, which is the basic unit of matter, consisting of a dense nucleus of protons and neutrons and a cloud of electrons surrounding it.

  • Atomic bomb

    See entry for Nuclear weapon

  • Atomic energy

    See entry for Nuclear energy.

  • Atomic Energy Act of 1954

    A piece of legislation that governs the development, utilization, and disposal of U.S. nuclear materials and facilities, as well as U.S. nuclear cooperation with other countries. See also the entry for Nuclear Cooperation (Section123) Agreement.

  • Atoms for Peace

    A U.S. program announced by President Dwight D. Eisenhower at the United Nations on 8 December 1953 to share nuclear materials and technology for peaceful purposes with other countries. This program required countries receiving nuclear materials to agree to inspections of the transferred technology to ensure it was not used for military purposes. The program was formally established in 1954, following the passage of the Atomic Energy Act, and ended abruptly in 1974 following India’s first nuclear test.

  • Attribution

    Refers to the conclusive determination of the origin of a certain nuclear material following an investigation utilizing multiple methods, likely including forensics. See entry for (nuclear) forensics.

  • Aum Shinrikyo

    A Japanese religious cult that attempted six failed biological attacks (five using incorrectly produced botulinum toxin, and one using incorrectly produced anthrax), and 12 chemical attacks (five using sarin, five using VX, one using phosgene, and one using hydrogen cyanide) from 1990 to 1995. The deadliest of these attacks was the sarin attack on the Tokyo subway system, which killed 12 people and injured 1,039 people on 20 March 1995.  Under cult leader Shoko Asahara, Aum Shinrikyo’s membership numbered in the tens of thousands, and the cult held assets in the range of $300 million to $1 billion.

  • Australia Group (AG)

    Established in 1985 to limit the spread of chemical and biological weapons (CBW) through export controls on chemical precursors, equipment, agents, and organisms.


  • Ballistic missile

    A delivery vehicle powered by a liquid or solid fueled rocket that primarily travels in a ballistic (free-fall) trajectory.  The flight of a ballistic missile includes three phases: 1) boost phase, where the rocket generates thrust to launch the missile into flight; 2) midcourse phase, where the missile coasts in an arc under the influence of gravity; and 3) terminal phase, in which the missile descends towards its target.  Ballistic missiles can be characterized by three key parameters – range, payload, and Circular Error Probable (CEP), or targeting precision.  Ballistic missiles are primarily intended for use against ground targets.

  • Ballistic missile defense (BMD)

    All active and passive measures designed to detect, identify, track, and defeat incoming ballistic missiles, in both strategic and theater tactical roles, during any portion of their flight trajectory (boost, post-boost, mid-course, or terminal phase) or to nullify or reduce their effectiveness in destroying their targets.

  • Baruch Plan

    Initially known as the Acheson-Lilienthal proposal, this was a U.S. initiative to outlaw nuclear weapons and to internationalize global stocks of fissile material for use in peaceful nuclear programs. After Bernard Baruch proposed the plan in 1946 at the United Nations, the United States and the Soviet Union held negotiations on the program but never reached agreement.

  • Beta particle

    A charged particle emitted from a nucleus during certain types of radioactive decay, with a mass much smaller than that of a proton or a neutron. A negatively charged beta particle is identical to an electron. A positively charged beta particle is called a positron. Large amounts of beta radiation may cause skin burns, and beta emitters are harmful if they enter the body. Beta particles may be stopped by thin sheets of metal or plastic.

  • Bilateral

    Negotiations, arrangements, agreements, or treaties that affect or are between two parties—and generally two countries.

  • Binary chemical weapon

    1. A munition in which two or more relatively harmless chemical substances, held in separate containers, react when mixed or combined to produce a more toxic chemical agent. The mixing occurs either in-flight, for instance in a chemical warhead attached to a ballistic missile or gravity bomb, or on the battlefield immediately prior to use. The mechanism has significant benefits for the production, transportation and handling of chemical weapons, since the precursor chemicals are usually less toxic than the compound created by combining them.  Binary weapons for sarin and VX are known to have been developed; or
    2. A munition containing two toxic chemical agents.  The United Kingdom combined chlorine and sulfur chloride during World War I and the United States combined sulfur mustard and lewisite. This definition is less commonly used.
  • Biological and Toxin Weapons Convention (BTWC)

    The Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on Their Destruction (BTWC) prohibits the development, production, or stockpiling of bacteriological and toxin weapons. Countries must destroy or divert to peaceful purposes all agents, toxins, weapons, equipment, and means of delivery within nine months after the entry into force of the convention. The BTWC was opened for signature on April 10, 1972, and entered into force on March 26, 1975. In 1994, the BTWC member states created the Ad Hoc Group to negotiate a legally binding BTWC Protocol that would help deter violations of the BTWC. The draft protocol outlines a monitoring regime that would require declarations of dual-use activities and facilities, routine visits to declared facilities, and short-notice challenge investigations.

  • Biological weapon (BW)

    Biological weapons use microorganisms and natural toxins to produce disease in humans, animals, or plants.  Biological weapons can be derived from: bacteria (anthrax, plague, tularemia); viruses (smallpox, viral hemorrhagic fevers); rickettsia (Q fever and epidemic typhus); biological toxins (botulinum toxin, staphylococcus enterotoxin B); and fungi (San Joaquin Valley fever, mycotoxins). These agents can be deployed as biological weapons when paired with a delivery system, such as a missile or aerosol device.

  • Blend-down

    See entry for Downblending.

  • Blister agent

    Blister agents (or vesicants) are chemical agents that cause victims to develop burns or blisters (“vesicles”) on their skin, as well as eyes, lungs, and airway irritation. Blister agents include mustard, lewisite, and phosgene, and are usually dispersed as a liquid or vapor. Although not usually fatal, exposure can result in severe blistering and blindness. Death, if it occurs, results from neurological factors or massive airway debilitation.

  • Blood agent

    Blood agents are chemical agents that enter the victim’s blood and disrupt the body’s use of oxygen. Arsenic-based blood agents do so by causing red blood cells to burst, and cyanide-based blood agents do so by disrupting cellular processing of oxygen.  Arsine, cyanogen chloride (CK), and hydrogen cyanide (AC) are colorless gasses, while sodium cyanide (NaCN) and potassium cyanide (KCN) are crystalline.  Hydrogen cyanide (CK) was used as a genocidal agent by Nazi Germany, and may have also been used by Iraq during the Iran-Iraq War and against the Kurdish city of Halabja.  At high doses, death from cyanide poisoning occurs within minutes.

  • Boiling water reactor

    A type of light water nuclear reactor where the same loop of water serves as a moderator, a coolant for the core, and a steam source for the turbine.

  • Bomber

    An aircraft carrying conventional or nuclear bombs, or conventionally or nuclear-armed cruise missiles, for use against ground or sea targets.

  • Boosted fission nuclear weapon

    A type of nuclear weapon with a higher explosive yield than a regular fission weapon. A small amount of fusion fuel in the weapon increases the neutron flux, leading to a larger amount of the fissionable material undergoing fission, typically resulting in a higher yielding weapon.

  • Booster

    The auxiliary part of a propulsion system of a missile that supplies the thrust during the launch and initial phase of a flight.

  • Boost-phase

    The part of a ballistic missile’s flight path that begins at launch, and may last from five minutes to 80 seconds depending on the sophistication of the missile. During the boost phase, the booster and sustainer engines operate, and the warheads have not yet been deployed.

  • Botulinum Toxin

    Botulism is caused by exposure to botulinum toxin (a neurotoxin).  Most often caused by eating contaminated foods, botulinum poisoning prevents the human nervous system from transmitting signals, resulting in paralysis, and eventually death by suffocation.  Botulinum toxin is the most toxic known substance. 15,000 times more toxic than VX nerve gas, mere nanograms of botulinum toxin will kill an adult human.  A significant bioweapons concern, botulinum toxin has been investigated as a weapon by Japan, the Soviet Union, the United States, Iraq and unsuccessfully by the Japanese cult Aum Shinrikyo.

  • Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC)

    This bilateral safeguards agency was established under an agreement between Argentina and Brazil to verify the exclusively peaceful use of nuclear energy in each country. The agreement establishing the agency was signed in Guadalajara, Mexico, on July 18, 1991.

  • Bunker Busters

  • BZ

    An incapacitating agent, BZ causes delirium at very low doses. Victims will drift in and out of delirium, during which they will appear to be in a “waking dream” state characterized by staring, muttering, shouting, and hallucinations.  BZ is a crystalline solid and can be delivered as a thermal vapor or dissolved into a solvent and delivered as a liquid.  Although the United States previously weaponized BZ, its unpredictability led to its diminished role in the American CW program, and all stocks were destroyed by 1990. The Former Yugoslavia and South Africa also reportedly produced BZ and BZ-like agents.


  • Cairo Declaration on the Denuclearization of Africa

    The Declaration on the Denuclearization of Africa was adopted at the first Assembly of Heads of States and Government of the Organization of African Unity (OAU) in Cairo in July 1964. The declaration called upon all states to respect the continent of Africa as a nuclear-weapon-free zone, and committed the African states to negotiate an international agreement, to be concluded under the auspices of the United Nations, not to manufacture or acquire nuclear weapons. The declaration was submitted to the United Nations General Assembly during its 1965 session.

  • Camp David

    A retreat to the northwest of Washington, DC, that is used by the president of the United States. Two framework agreements providing for a peace treaty between Egypt and Israel, and peace in the Middle East more broadly, were negotiated at Camp David and are known as the Camp David Accords.

  • Canberra Commission on the Elimination of Nuclear Weapons

    Established by Australia in November 1995, the commission was created to develop ideas and propose practical steps to create a nuclear weapon-free world. On August 31, 1996, the Commission presented its findings to the Australian government, which then submitted the Canberra Report to the UN General Assembly and the Conference on Disarmament.

  • CDC (Centers for Disease Control and Prevention)

    The lead U.S. federal agency responsible for protecting the health and safety of American citizens at home and abroad, providing credible information to enhance health decisions, and promoting health through strong partnerships. The Office of Public Health Preparedness and Response is focused on minimizing the threat to health from terrorist acts, accidents, and chemical, biological and radiological threats.

  • Central and Eastern Europe NWFZ

    In July 1996, Belarus and Ukraine called for a Central and Eastern European NWFZ. However, several key countries necessary to the success of the proposal were interested in joining NATO, and therefore opposed an NWFZ.

  • Central Asia Nuclear-Weapon-Free Zone (CANWFZ)

    The Central Asia Nuclear-Weapons-Free-Zone (CANWFZ) includes all five Central Asian states: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The foreign ministers of the five countries signed the treaty establishing the zone on 8 September 2006 at the former Soviet nuclear test site in Semipalatinsk, Kazakhstan. The treaty entered into force on 21 March 2009.

  • Chain reaction (fission)

    A process in which neutrons are absorbed by fissionable material and the neutrons released as a result of fission go on to cause more fissions.  A self-sustaining chain reaction is one where the number of neutrons released from fission in one period of time (or generation) is enough to cause the same number of fissions in the following generation, taking into account that some neutrons will be absorbed by non-fissionable material or escape the region of fissionable material.  Nuclear reactors, as well as nuclear weapons, utilize chain reactions.

  • Challenge inspection

    An inspection triggered by a suspected violation of a treaty or agreement.  The inclusion of this type of provision in an agreement increases the likelihood of detecting weapons at sites not declared in the data exchanged under that agreement.

  • Charged particle

    A particle with a positive or negative electric charge.

  • Chemical Agent Precursor

    Any chemical reactant which takes part at any stage in the production by whatever method of a chemical agent. This includes any key component of a binary or multi-component chemical system.  Common precursors to toxic chemicals are listed alongside the agents in the OPCW Schedules of Chemicals.  Many precursors controlled through nonproliferation initiatives also have legitimate commercial uses.

  • Chemical Weapon (CW)

    The Organization for the Prohibition of Chemical Weapons defines a chemical weapon as any of the following: 1) a toxic chemical or its precursors; 2) a munition specifically designed to deliver a toxic chemical; or 3) any equipment specifically designed for use with toxic chemicals or munitions.  Toxic chemical agents are gaseous, liquid, or solid chemical substances that use their toxic properties to cause death or severe harm to humans, animals, and/or plants. Chemical weapons include blister, nerve, choking, and blood agents, as well as non-lethal incapacitating agents and riot-control agents.  Historically, chemical weapons have been the most widely used and widely proliferated weapon of mass destruction.

  • Chemical Weapons Convention (CWC)

    The Chemical Weapons Convention (CWC) requires each state party to declare and  destroy all the chemical weapons (CW) and CW production facilities it possesses, or that are located in any place under its jurisdiction or control, as well as any CW it abandoned on the territory of another state. The CWC was opened for signature on 13 January 1993, and entered into force on 29 April 1997.

  • Chloracetophenone (CN)

    Distributed under the trade name Mace, CN is a tear agent that, as a solid or powder, can be delivered as smoke, powder, or liquid.  CN produces eye irritation and tearing, as well as respiratory irritation.  CN is typically used as a riot control agent, and is rarely lethal.

  • Choking agent

    A chemical weapon which attacks lung tissue when inhaled, leading to respiratory failure. Choking agents cannot be absorbed through the skin and generally do not cause external injuries. Examples include chlorine and phosgene.

  • Cholera

    A disease of the digestive tract caused by the bacteria Vibrio cholerae. A water-borne disease, cholera infections usually occur via contaminated water or foods. Cholera causes severe diarrhea followed by severe dehydration, and can result in death within hours or days.  Sanitation in the developed world has greatly lessened cholera’s public health impact. Unit 731 of the Japanese Imperial Army used cholera against the Chinese military and civilian populations during World War II.

  • Circular Error Probable

    An indicator of a weapon system’s accuracy, measured as the radius of the circle in which ½ of all warheads fired at a target will fall.

  • CIS

    The Commonwealth of Independent States (CIS) is an association of former Soviet states that coordinates the facilitation of free movement of goods, services, labor force, and capital among member states and promotes cooperation on security matters.

  • Command, control, communication and intelligence (C3I)

    Command, control, communications, and intelligence systems are the integrated combinations of military command information processing, communications network, and intelligence gathering subsystems (including surveillance, warning, and identification subsystems). These combined technologies are designed to provide timely and adequate data required to plan, direct, and control military forces and operations. Sometimes referred to as C4I when “computers” are included.

  • Compliance provisions

    Provisions included in a treaty or legally binding agreement to ensure that parties abide by the requirements or restrictions set out in the treaty. Compliance provisions may, among others, include on-site inspections to detect violations, and punitive measures such as sanctions if a violation occurs.

  • Comprehensive Nuclear-Test-Ban Treaty (CTBT)

    Opened for signature in 1996 at the UN General Assembly, the CTBT prohibits all nuclear testing if it enters into force. The treaty establishes the Comprehensive Test Ban Treaty Organization (CTBTO) to ensure the implementation of its provisions and verify compliance through a global monitoring system upon entry into force. Pending the treaty’s entry into force, the Preparatory Commission of the CTBTO is charged with establishing the International Monitoring System (IMS) and promoting treaty ratifications. CTBT entry into force is contingent on ratification by 44 Annex II states.

  • Conference on Disarmament (CD)

    The CD is an international forum focused on multilateral disarmament efforts. Although it reports to the UN General Assembly and has a relationship with the United Nations, it adopts its own rules of procedure and agenda, giving it some degree of independence. The CD has a permanent agenda devoted to the negotiation of disarmament issues. The CD and its predecessors have negotiated major nonproliferation and disarmament agreements such as the NPT, the BTWC, the CWC, and the CTBT. In recent years, the CD has focused on negotiating a treaty banning the production of fissile material for nuclear weapons or other nuclear explosive devices; the prevention of an arms race in outer space (PAROS); and negative security assurances.

  • Confidence- (and Security-) Building Measures (CSBMs)

    Tools that states can use to reduce tensions and avert the possibility of military conflict. Such tools include information (e.g., the size of military forces); communication (e.g., “hot lines” or direct lines between capitals); constraints (e.g., demilitarized zones); notification (e.g., prohibitions on activities that have not been notified in advance); and access (e.g., on-site inspections) measures. CSBMs normally precede the negotiation of formal arms control agreements or are added to arms control agreements to strengthen them. See entries for Arms Control, Transparency Measures, and Verification.

  • Containment structure

    An enclosure around a nuclear reactor to confine fission products that otherwise might be released into the atmosphere in the event of an accident.

  • Conventional weapons

    Weapons and military equipment, including small arms and light weapons, tanks, artillery rockets,  aircraft, torpedoes, mines and cluster munitions that do not use biological agents, chemical agents, nuclear explosives, or kinetic energy weapons to damage targets.

  • Convention for the Suppression of the Financing of Terrorism

    The Convention for the Suppression of the Financing of Terrorism requires each State party to take appropriate measures, in accordance with its domestic legal principles, for the detection and freezing, seizure or forfeiture of any funds used or allocated for the purposes of committing acts of terrorism. The Convention was adopted by the General Assembly on December 9, 1999 and entered into force on 10 April 2002.

  • Convention on Nuclear Safety (CNS)

    The Convention on Nuclear Safety commits states operating nuclear power plants to establish and maintain a regulatory framework to govern the safety of nuclear installations. The Convention was adopted in 1994 and obligates parties to carry out comprehensive and systematic safety assessments of installations and ensure that the physical state and operations of installations are in accordance with the requirements of the Convention.

  • Convention on the Physical Protection of Nuclear Material (CPPNM)

    Obliges parties to ensure that during international transport across their territory, or on ships or aircraft under their jurisdiction, civil nuclear materials are protected according to agreed standards. The convention also provides a framework for international cooperation on the protection, recovery, and return of stolen nuclear material, and on the application of criminal sanctions against persons who commit crimes involving nuclear material. The CPPNM opened for signature on 3 March 1980 and entered into force on 8 February 1987. The Amendment to the CPPNM extended the convention’s scope to also cover the physical protection of nuclear material in domestic use, in storage, and during transport, and of nuclear facilities used for peaceful purposes, and provided for additional cooperation between states.

  • Coolant

    A fluid circulated through a nuclear reactor to remove or transfer heat. The most commonly used coolant in the United States is water. Other coolants include heavy water, air, carbon dioxide, helium, liquid sodium, and a sodium-potassium alloy.

  • Cooperative Threat Reduction (Nunn-Lugar) Program

    A U.S. Department of Defense (DOD) program established in 1992 by the U.S. Congress, through legislation sponsored primarily by Senators Sam Nunn and Richard Lugar. It is the largest and most diverse U.S. program addressing former Soviet Union weapons of mass destruction threats. The program has focused primarily on: (1) destroying vehicles for delivering nuclear weapons (e.g., missiles and aircraft), their launchers (such as silos and submarines), and their related facilities; (2) securing former Soviet nuclear weapons and their components; and (3) destroying Russian chemical weapons. The term is often used generically to refer to all U.S. nonproliferation programs in the former Soviet Union—and sometimes beyond— including those implemented by the U.S. Departments of Energy, Commerce, and State. The program’s scope has expanded to include threat reduction efforts in geographical areas outside the Former Soviet Union.

  • Coordinating Committee for Multilateral Export Controls (COCOM)

    Based in Paris, this organization was established in 1949 to restrict the sale of goods to Warsaw Pact countries. Its 17 members included Japan and all of the NATO countries except Iceland. Following the end of the Cold War, many of COCOM’s restrictions on Eastern Europe were lifted. COCOM ceased to exist in 1994, and in 1995 the organization was superseded by the Wassenaar Arrangement on Export Controls for Conventional Arms and Duel-Use Goods and Technologies. See entry for Wassenaar Arrangement.

  • Core

    The central part of a nuclear reactor where nuclear fission occurs. It contains the fuel, control rods, moderator, coolant, and support structures.

  • Counterforce targeting

    War planning that envisions strikes on an enemy’s military and industrial targets.

  • Countervalue targeting

    War planning that envisions strikes on an enemy’s civilian population centers.

  • Critical

    A state where the number of neutrons in each period of time, or generation, remains constant.  When a nuclear reactor is “steady-state,” or operating at normal power levels for extended periods of time, it is in this state.

  • Critical infrastructure

    According to U.S. Presidential Decision Directive-63 of May 1998, critical infrastructure is defined as “those physical and cyber-based systems essential to the minimum operations of the economy and government.” The term is generally used in the context of discussing the vulnerabilities of, or the strategies to protect from physical and cyber attacks, systems such as “telecommunications, energy, financial services, manufacturing, water, transportation, health care, and emergency services,” according to U.S. Executive Order 13231 of October 2001.

  • Critical mass

    The minimum amount of concentrated fissionable material required to sustain a chain reaction.  See entry for Chain reaction.

  • Cruise missile

    An unmanned self-propelled guided vehicle that sustains flight through aerodynamic lift for most of its flight path. There are subsonic and supersonic cruise missiles currently deployed in conventional and nuclear arsenals, while conventional hypersonic cruise missiles are currently in development. These can be launched from the air, submarines, or the ground. Although they carry smaller payloads, travel at slower speeds, and cover lesser ranges than ballistic missiles, cruise missiles can be programmed to travel along customized flight paths and to evade missile defense systems.

  • Cruise missile submarines (SSGN)

    SSGN is the United States Navy hull classification symbol for a nuclear-powered cruise missile submarine. The SS denotes a submarine, the G denotes a “guided missile,” and the N denotes nuclear power. The Soviet Navy had several submarines that were also called SSGNs by Western observers.

  • CS

    A widely used riot-control agent (RCA) and the standard RCA of the U.S. Army.  CS causes tearing and a burning sensation in the eyes, as well as respiratory irritation and tightness.  Skin exposure results in tingling or burning.  CS is a white solid and can be dispersed in powdered form, as a liquid solution, or as smoke. CS is rarely lethal, and is considered to be both a more effective and less toxic RCA than CN.

  • Cyanogen chloride (CK)

    A blood agent, cyanogen chloride enters the bloodstream and inhibits the distribution and use of oxygen throughout the body.  Organ systems sensitive to low oxygen levels, such as the central nervous system, the cardiovascular system, and the pulmonary system, are particularly affected by cyanide poisoning.   At non-lethal dosages, exposure to cyanogen chloride causes eye, skin, and lung irritation. Cyanogen chloride is easier to deliver but less toxic than hydrogen cyanide.


  • De-activate

    To remove a weapon from operational status for an indefinite period.

  • De-alert

    To reduce the level of readiness to launch of nuclear weapons systems. Measures include removing nuclear warheads from missiles, and storing the warheads separately from the missiles.

  • Decontamination

    The reduction or removal of radioactive material from a structure, area, object, or person. Decontamination measures include: treating the surface to remove or decrease the contamination; letting the material stand so that the radioactivity decreases over time as a result of natural radioactive decay; or covering the contamination to shield or attenuate the radiation emitted.

  • (Department of) Health and Human Services

    The Department of Health and Human Services (HHS) is the United States government’s principal agency for protecting the health of all Americans and providing essential human services. The Office of Emergency Preparedness (OEP) of the HHS assists local public health agencies, health care organizations and public safety officials to be able to respond swiftly and effectively to significant public health threats, especially bioterrorism.

  • (Department of) Homeland Security

    A cabinet-level U.S. federal agency created in the wake of the 11 September 2001 terrorist attacks on the United States. The DHS consolidated the activities of all pre-existing non-military government agencies concerned with border control, prevention of terrorism, and emergency response.

  • Deployment

    The positioning of military forces – conventional and/or nuclear – in conjunction with military planning.

  • Design Basis Threat (DBT)

    Defined by the U.S. Nuclear Regulatory Commission as the “profile of the type, composition, and capabilities of an adversary.” The NRC and U.S. nuclear facilities licensed for operation use the DBT as a basis for designing systems to protect against acts of radiological sabotage, and to prevent the theft of special nuclear material.

  • De-targeting

    Removing the targeting information from, or substituting ocean-area target coordinates on, a ballistic missile, in order to reduce the consequences of an accidental or unintentional launch. De-targeting cannot be verified, and missiles can be rapidly re-targeted.

  • Deterrence

    The actions of a state or group of states to dissuade a potential adversary from initiating an attack or conflict through the credible threat of retaliation. To be effective, a deterrence strategy should demonstrate to an adversary that the costs of an attack would outweigh any potential gains. See entry for Extended deterrence.

  • Diesel-electric submarine

    A submarine with a diesel-electric transmission. Diesel-electric transmissions require access to oxygen for the diesel generator to charge the submarine’s batteries or drive the motor.  This type of submarine is thus louder and must surface more frequently than a nuclear-powered submarine.  A diesel-electric submarine can fire conventional cruise missiles against land targets, and in theory, can also carry nuclear-tipped cruise missiles. Diesel-electric submarines are significantly cheaper to build and purchase than nuclear-powered vessels, which makes them the vessel of choice for smaller navies.

  • Diffusion

    A technique for uranium enrichment in which the lighter Uranium 235 isotopes in UF6 gas move through a porous barrier more rapidly than the heavier Uranium 238 isotopes.

  • Diphenylchloroarsine (DA)

    A vomiting agent, DA can be used as a riot-control agent or to force enemies to remove their protective gear.  A white odorless crystal, DA and other vomiting agents are typically delivered as aerosols.  Currently, DA is less prominent than other more easily weaponized agents.

  • Diphosgene

    A choking agent, diphosgene causes lung irritation leading to the build-up of fluid in the lungs.  A colorless liquid at room temperature, diphosgene, like phosgene, smells like hay or young corn, and was delivered using artillery shells during World War I.

  • Dirty bomb

    An informal term for a radiological dispersal device (RDD), a device pairing conventional explosives with radiological materials. Once detonated, the conventional explosives disperse the radioactive material, radioactively contaminating the target area.

  • Disarmament

    Though there is no agreed-upon legal definition of what disarmament entails within the context of international agreements, a general definition is the process of reducing the quantity and/or capabilities of military weapons and/or military forces.

  • Dismantlement

    Taking apart a weapon, facility, or other item so that it is no longer functional.

  • Diversion

    The clandestine removal or appropriation of materials or technologies for use in projects or weapons programs that violate either a state’s treaty obligations or an end use agreement reached between the state and the country from which the material or technology originated.

  • DNA

    Deoxyribonucleic acid. DNA molecules carry the genetic information necessary for the organization and functioning of most living cells, and control the inheritance of genetic characteristics.

  • Downblending

    Refers to the process of blending down HEU to LEU. This is done by mixing HEU and the blendstock (of natural, depleted, or slightly enriched uranium) in either liquid or gas form. See highly enriched uranium and low enriched uranium.

  • Downloading

    The removal of some of the warheads from a Multiple Independently-targetable Reentry Vehicle (MIRV) ballistic missile.  See Multiple Independently-targetable Reentry Vehicle.

  • Dual-use item

    An item that has both civilian and military applications. For example, many of the precursor chemicals used in the manufacture of chemical weapons have legitimate civilian industrial uses, such as the production of pesticides or ink for ballpoint pens.


  • EAPC

    Created in 1997, the Euro-Atlantic Partnership Council (EAPC) succeeded the North Atlantic Cooperation Council, and brings together the 26 NATO allies and 20 partners in a forum providing for regular consultation and cooperation. The EAPC meets periodically at the level of ambassadors and foreign and defense ministers; when appropriate, heads of state and government of the 49 members also meet.

  • Eighteen-Nation Disarmament Committee (ENDC)

    The predecessor to the UN Conference on Disarmament in Geneva, the ENDC existed from 1962 to 1968, and hosted most of the negotiations concerning the NPT text. It consisted of five Western countries, five Eastern (Soviet bloc) countries, and eight non-aligned countries, with the United States and Soviet Union as co-chairs.

  • Electromagnetic Pulse (EMP)

    A sharp pulse of radio-frequency (long wavelength) radiation produced when an explosion occurs in an asymmetrical environment, especially at or near the earth’s surface or at high altitudes. The intense electric and magnetic fields can damage unprotected electrical and electronic equipment over a large area.

  • Electron

    An elementary particle with a negative charge and a mass of 0.00055 amu (atomic mass units). Electrons surround the positively charged nucleus and determine the chemical properties of the atom.

  • Enriched uranium

    Uranium with an increased concentration of the isotope U-235, relative to natural uranium. Natural uranium contains 0.7 percent U-235, whereas nuclear weapons typically require uranium enriched to very high levels (see the definitions for “highly enriched uranium” and “weapons-grade”).  Nuclear power plant fuel typically uses uranium enriched to 3 to 5 percent U-235, material that is not sufficiently enriched to be used for nuclear weapons.

  • Entry into force

    The moment at which all provisions of a treaty are legally binding on its parties. Every treaty specifies preconditions for its entry into force. For example, the NPT specified that it would enter into force after the United States, the United Kingdom, and the Soviet Union (the Depository governments) and 40 other countries ratified the treaty, an event that occurred on 5 March 1970. See entries for Signature, Ratification.

  • European Atomic Energy Community (Euratom)

    Launched in 1958 to facilitate the development of nuclear energy for peaceful purposes within the European Community.

  • (European) Phased Adaptive Approach (EPAA)

    This approach to the organization of ballistic missile defense efforts in Europe was announced by U.S. President Barack Obama’s administration in September 2009. It originally envisioned four phases of technological development and deployment between 2011 and 2020. U.S. Defense Secretary Chuck Hagel announced in March 2013 that the fourth and final phase of EPAA would not be implemented, citing development problems and funding cuts. The EPAA is reliant on sea-based Aegis cruisers with SM-3 interceptors and land-based SM-3 interceptor technology. At the 2010 Lisbon summit, NATO formally endorsed the EPAA.

  • Export control

    National laws or international arrangements established to restrict the sale of certain goods to certain countries, or to ensure that safeguards or end-use guarantees are applied to the export and sale of sensitive and dual-use technologies and materials. See entry for Dual-use

  • Extended deterrence

    A country protected from potential adversaries by the nuclear weapons’ backed security guarantee of an ally is said to be under an (extended deterrence) nuclear umbrella. See entry for Deterrence.


  • Fallout

    The process of the descent to the earth’s surface of particles contaminated with radioactive material from a radioactive cloud. The term is also applied in a collective sense to the contaminated particulate matter itself. The early (or local) fallout is defined, somewhat arbitrarily, as those particles which reach the earth within 24 hours after a nuclear explosion. The delayed (or worldwide) fallout consists of the smaller particles which ascend into the upper troposphere and stratosphere, to be carried by winds to all parts of the earth. The delayed fallout is brought to earth, mainly by rain and snow, over extended periods ranging from months to years, and can contaminate the animal food-chain.

  • FBI (Federal Bureau of Investigation)

    The principal investigative arm of the United States Department of Justice. The mission of the FBI is to uphold the law through the investigation of violations of federal criminal law; to protect the United States from foreign intelligence and terrorist activities; to provide leadership and law enforcement assistance to federal, state, local, and international agencies; and to perform these responsibilities in a manner that is responsive to the needs of the public and is faithful to the Constitution of the United States.

  • FEMA (Federal Emergency Management Agency)

    A U.S. federal agency that can be called upon to help when the president declares a disaster. The governor of the state in question must request assistance from the president before FEMA can respond. Disasters are “declared” after hurricanes, tornadoes, floods, earthquakes, or other similar events strike a community. In March 2003, FEMA became a part of the Department of Homeland Security.

  • First Committee

    The first of six Main Committees of the United Nations General Assembly which deals with all issues related to disarmament and international security. The First Committee on Disarmament and International Security meets every year in October for four to five weeks after the General Assembly’s general debate. See entry for United Nations General Assembly.

  • First responders

    Emergency personnel who are the first to arrive at the scene of an incident, including firefighters, police, and emergency medical technicians (EMTs). In most cases, these are the local authorities in the affected area.

  • First strike

    The launch of a surprise attack intended to considerably weaken or destroy an adversary’s military infrastructure or nuclear forces, and thus severely reduce the adversary’s ability to attack or retaliate.

  • First-use

    The introduction of nuclear weapons, or other weapons of mass destruction, into a conflict. In agreeing to a “no-first-use” policy, a country states that it will not use nuclear weapons first, but only under retaliatory circumstances. See entry for No-First-Use

  • Fissile isotope

    Isotopes capable of undergoing fission by absorbing neutrons at any energy, including low energies (also referred to as “thermal” energies). Uranium-233, Uranium-235, and Plutonium-239 are all fissile isotopes.

  • Fissile material

    A type of fissionable material capable of sustaining a chain reaction by undergoing fission upon the absorption of low-energy (or thermal) neutrons.  Uranium-235, Plutonium-239, and Uranium-233 are the most prominently discussed fissile materials for peaceful and nuclear weapons purposes.

  • Fissile Material Cut-off Treaty (FMCT)

    Treaty currently under discussion in the Conference on Disarmament (CD) to end the production of weapons-usable fissile material (highly enriched uranium and plutonium) for nuclear weapons.

  • Fission

    The splitting of the nucleus of a heavy atom into two lighter nuclei (called fission fragments). It is accompanied by the release of neutrons, gamma rays, and fission fragments with large amounts of kinetic energy.  It is usually triggered by absorption of a neutron, but in some cases may be induced by protons, gamma rays or other particles

  • Fissionable isotope

    An isotope whose nuclei can undergo fission, but requires the absorption of high-energy neutrons. Uranium-238 is an example of a fissionable isotope.

  • Fission bomb

    A nuclear bomb based on the concept of releasing energy through the fission (splitting) of heavy isotopes, such as Uranium-235 or Plutonium-239.

  • Fission products

    Nuclei formed by the fission of heavy elements. Almost all are radioactive. Examples include strontium-90 and cesium-137.

  • Fleet ballistic missile submarine (SSBN)

    A nuclear-powered submarine designed to deliver ballistic missile attacks against assigned targets from either a submerged or surfaced condition.

  • Floating nuclear power plant

    A technology financed by Russia’s Rosenergoatom corporation that involves the development of a floating barge designed to carry several nuclear reactors (used in Russia’s nuclear icebreakers), and facilities for the storage of nuclear waste. The project envisages the domestic use and export of these plants to provide a power generation capability to remote regions, and to enhance resource extraction efforts.

  • Force structure

    The configuration of a country’s nuclear or conventional forces. For example, in the United States and Russia, nuclear forces are structured in a triad, with nuclear warheads deployed on bombers, land-based missiles, and sea-based missiles.

  • Fuel bank

    Refers to programs to set aside a guaranteed stockpile of LEU fuel, with its release typically under IAEA control, to mitigate the effects of possible disruptions in a country’s LEU fuel supplies.  Fuel bank concepts are typically envisioned as diminishing the incentive for countries to develop indigenous uranium enrichment capabilities.

  • Fuel Cycle

    A term for the full spectrum of processes associated with utilizing nuclear fission reactions for peaceful or military purposes.  The “front-end” of the uranium-plutonium nuclear fuel cycle includes uranium mining and milling, conversion, enrichment, and fuel fabrication.  The fuel is used in a nuclear reactor to produce neutrons that can, for example, produce thermal reactions to generate electricity or propulsion, or produce fissile materials for weapons. The “back-end” of the nuclear fuel cycle refers to spent fuel being stored in spent fuel pools, possible reprocessing of the spent fuel, and ultimately long-term storage in a geological or other repository.

  • Full-scope safeguards

    Refers to a set of measures implemented by the International Atomic Energy Agency to detect, in a timely manner, the diversion of a significant quantity of nuclear material by monitoring various stages in the nuclear fuel cycle of a non-nuclear weapon state.  See entries for Information Circular 66, Information Circular 153, and Safeguards.

  • Fundamentalism

    An approach to religious observance that favors a literalist or extreme interpretation of, and strict adherence to, a religion’s core texts. A common theme is the attempt to return to the simplicity of belief and interpretation which is believed to reflect the original character of the religion’s founder or founders. This approach is often combined with religiously justified political agendas which because they are divinely inspired, are not subject to negotiation or discussion. Fundamentalism is not specific to any single religion, and fundamentalist movements can be found within Islam, Hinduism, Christianity, and Judaism among other religions.

  • Fusion

    Nuclear fusion is a type of nuclear reaction in which two atomic nuclei combine to form a heavier nucleus, releasing energy. For a fusion reaction to take place, the nuclei, which are positively charged, must have enough kinetic energy to overcome their electrostatic force of repulsion (also called the Coulomb Barrier). Thermonuclear fusion of deuterium and tritium will produce a helium nucleus and an energetic neutron. This is one basis of the Hydrogen Bomb, which employs a brief, uncontrolled thermonuclear fusion reaction. A great effort is now underway to harness thermonuclear fusion as a source of power.


  • G-8 Global Partnership Against the Spread of Weapons of Mass Destruction

    Launched in 2002 at the G-8 Summit in Kananaskis, the G-8 Global Partnership is a multilateral initiative for financial commitments to implement and coordinate chemical, biological, and nuclear threat reduction activities on a global scale. Originally granted a ten-year lifespan and focused primarily on activities in the former Soviet Union, the Partnership has since been extended beyond 2012; it has also expanded its membership and scope of activities globally.

  • Gamma radiation

    High-energy, short wavelength, electromagnetic radiation emitted from the nucleus. Gamma radiation frequently accompanies alpha and beta emissions and always accompanies fission. Gamma rays are very penetrating and are best stopped or shielded by dense materials, such as lead or depleted uranium. Gamma rays are similar to x-rays but have higher energies.

  • Geneva Protocol

    Formally known as the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, this protocol prohibits the use in war of asphyxiating, poisonous, or other gases, and bans bacteriological warfare. It was opened for signature on 17 June 1925.

  • Global Initiative to Combat Nuclear Terrorism (GICNT)

    The GICNT was announced by U.S. President George W. Bush and Russian President Vladimir Putin on 15 July 2006 in St. Petersburg, Russia. The initiative’s missions is to strengthen global capacity to prevent, detect, and respond to nuclear terrorism by conducting multilateral activities that strengthen the plans, policies, procedures, and interoperability of partner nations.

  • Global Strike Mission

    A mission assigned to U.S. STRATCOM in January 2003 aimed at providing the President of the United States with the option to order preemptive military strikes against high-value and mobile WMD targets with conventional or nuclear weapons.

  • Global Threat Reduction Initiative

    A program established by the U.S. National Nuclear Security Administration in May 2004 to identify, secure, remove, and/or facilitate the removal of vulnerable nuclear and radiological materials around the world. The GTRI incorporated, among other programs, longstanding U.S. efforts under the RERTR program to convert domestic and foreign research reactors from highly enriched uranium fuel to low-enriched uranium fuel.

  • Ground Based Interceptor (GBI)

    The ground-based missile intercept of the National Missile Defense (NMD) system proposed by the George W. Bush administration, the GBI would intercept incoming ballistic missile warheads outside the earth’s atmosphere (exo-atmospheric) and collide with the incoming ballistic missile, thereby destroying the missile. The GBI would consist of a multi-stage solid propellant booster and an exo-atmospheric kill vehicle.

  • Gun-type (nuclear) weapon

    A device in which two or more pieces of fissionable material, each smaller than a critical mass, are brought together very rapidly so as to form a supercritical mass which can explode as the result of a rapidly expanding fission chain reaction.


  • Half-life

    The time in which one half of the atoms of a particular radioactive substance decay. Measured half-lives vary from millionths of a second to billions of years, depending on the isotope.  Also called physical or radiological half-life.

  • Hazmat teams

    Specialists who respond to incidents involving hazardous materials.

  • HCOC

    The Hague Code of Conduct against Ballistic Missile Proliferation (HCOC), formerly known as The International Code of Conduct (ICOC), was adopted in 2002. The HCOC was established to bolster efforts to curb ballistic missile proliferation worldwide and to further delegitimize such proliferation by fostering consensus among states on how they should conduct their trade in missiles and dual-use items.

  • Hemorrhagic fever viruses

    A group of viruses that cause characteristic hemorrhaging (bleeding) resulting from damage to the vascular system and impairment of bodily regulation. The diseases caused by hemorrhagic fever viruses include Marburg, Ebola, Yellow fever, and Lassa fever.  Primarily found in rodents and arthropods, human outbreaks of viral hemorrhagic fevers are very rare and thus, they are less thoroughly understood than the more commonly occurring human viral diseases. The Soviet Union weaponized several hemorrhagic fever viruses including Marburg, Ebola, Lassa, and the New World arenaviruses Junin and Machupo. The United States weaponized Yellow fever and Rift Valley fever.  North Korea may have also weaponized hemorrhagic fever viruses.

  • HEU deal

    The United States and Russia concluded the Highly Enriched Uranium (HEU) Purchase Agreement in 1993. Under the terms of the agreement, the United States would purchase 500 tons of HEU over a 20-year period from the former Soviet weapons program, dilute it to low-enriched uranium, and sell it as fuel for nuclear power plants on the commercial market. The HEU Deal is also referred to as the “Megatons to Megawatts” program.

  • Hibakusha

    Hibakusha is the term widely used in Japan to refer to survivors of the World War II atomic bombings of Hiroshima and Nagasaki. The Japanese word translates literally to “explosion-affected people.”

  • High alert

    A state of readiness of nuclear forces sufficient to launch an immediate attack.

  • Highly enriched uranium (HEU)

    Refers to uranium with a concentration of more than 20% of the isotope U-235. Achieved via the process of enrichment.  See entry for enriched uranium.

  • Hiroshima

    The city in Japan where the first atomic bomb, “little boy,” was dropped on 6 August 1945 during World War II. More than 140,000 people were killed.

  • Horizontal proliferation of WMD

    See entry for Proliferation

  • Hydrogen bomb

    See entries for Nuclear weapon and Thermonuclear weapon.

  • Hydrogen cyanide (AC)

    A blood agent, hydrogen cyanide (AC) harms its victims by entering the bloodstream and disrupting the distribution and use of oxygen throughout the body.  This causes serious dysfunction in organ systems sensitive to low oxygen levels, such as the central nervous system, the cardiovascular system, and the pulmonary system.  Hydrogen cyanide can be disseminated as a liquid, aerosol, or gas.  Notoriously, Nazi Germany used hydrogen cyanide as a genocidal agent during the Holocaust.


  • Improvised nuclear device (IND)

    A device that uses a simple, untested design to attempt to create a nuclear explosion.

  • Incapacitating agent

    A chemical agent that causes psychological or mental effects in victims that prevent them from performing assigned missions, duties, or tasks. The effects of incapacitating agents dissipate or disappear over time. The United States previously stockpiled BZ as an incapacitating agent; LSD has also been investigated as an incapacitating agent.

  • India-Pakistan Agreement on Chemical Weapons

    Signed in 1992, the India-Pakistan Agreement on Chemical Weapons provides for “the complete prohibition of chemical weapons” in India and Pakistan.

  • India-Pakistan Non-Attack Agreement

    The India-Pakistan Non-Attack Agreement is a unique bilateral agreement that obligates India and Pakistan to refrain from undertaking, encouraging, or participating in actions aimed at causing destruction or damage to nuclear installations or facilities in each country.


    Refers to the International Nuclear Fuel Cycle Evaluation (INFCE) study conducted between 1977 and 1980. This study discussed multilateral approaches to the nuclear fuel cycle, the development of regional fuel-cycle facilities, and cooperation on the storage of plutonium.

  • Information Circular 153 (INFCIRC/153)

    An International Atomic Energy Agency (IAEA) document entitled “The Structure and Content of Agreements between the Agency and States Required in Connection with the Treaty on the Nonproliferation of Nuclear Weapons (NPT).” Established by the IAEA in April 1970 after the NPT entered into force. The document created the full-scope safeguards system whereby any non-nuclear weapon state party to the NPT agrees to establish and maintain a system of accounting and control of all nuclear material under its jurisdiction. Accordingly, non-nuclear weapon states which are party to or have signed but not ratified the NPT must conclude a safeguards agreement with the IAEA.

  • Information Circular 26 (INFCIRC/26)

    The first International Atomic Energy Agency (IAEA) safeguards system applicable to reactors rated less than 100 thermal megawatts, approved by the IAEA Board of Governors on 31 January 1961. It was revised in June 1963 to cover reactors of any size.

  • Information Circular 540 (INFCIRC/540)

    A document approved by the International Atomic Energy Agency (IAEA) in May 1997, called the “Model Protocol Additional to the Agreement(s) between States(s) and the International Atomic Energy Agency for the Application of Safeguards,” which supplements the INFCIRC/153. The Model Protocol grants IAEA inspectors additional physical access to sites of IAEA member states where nuclear material is or could be present, expands the use of unannounced inspections, and allows for the collection of environmental samples. The provisions in the protocol are also known as the “Program 93+2″. See entry for Additional Protocol.

  • Information Circular 66 (INFCIRC/66)

    The model safeguards agreement approved by the International Atomic Energy Agency in February 1965 to safeguard individual nuclear facilities. The guidelines were later revised to include reprocessing and fuel fabrication plants. It was most widely employed prior to the advent of nonproliferation treaties in the 1960s requiring full-scope safeguards.

  • Information-driven safeguards

    Refers to the IAEA knowledge-based approach to nuclear facility safeguards that involves, among other things, the development of state-specific evaluations and the analysis of all source intelligence.

  • Intelligence

    Information and data collected by a government to learn about other states,’ and non-state actors,’ capabilities and intentions.

  • Intercontinental ballistic missile (ICBM)

    A ballistic missile with a range greater than 5,500 km. See entry for ballistic missile.

  • Intermediate-Range Nuclear Forces (INF) Treaty

    A treaty between the United States and the former Soviet Union, signed on 8 December 1987, which entered into force on 1 June 1988. It aimed to eliminate and ban all ground-launched ballistic and cruise missiles with a range of between 300 and 3,400 miles (500 to 5,500 kilometers). The treaty required the United States and the Soviet Union to conduct inspections at each other’s sites during the elimination of treaty-limited items (TLI). By May 1991, all intermediate-range and shorter-range missiles, launchers, related support equipment, and support structures were eliminated.

  • International Atomic Energy Agency (IAEA)

    Founded in 1957 and based in Vienna, Austria, the IAEA is an autonomous international organization in the United Nations system. The Agency’s mandate is the promotion of peaceful uses of nuclear energy, technical assistance in this area, and verification that nuclear materials and technology stay in peaceful use. Article III of the Nuclear Non-Proliferation Treaty (NPT) requires non-nuclear weapon states party to the NPT to accept safeguards administered by the IAEA. The IAEA consists of three principal organs: the General Conference (of member states); the Board of Governors; and the Secretariat.

  • International Code of Conduct Against Ballistic Missiles (ICOC)

    A legally non-binding arrangement that was launched with the objective of preventing and curbing the proliferation of ballistic missile systems capable of delivering weapons of mass destruction. States adhering to the ICOC agree not to assist ballistic missile programs in countries suspected of developing biological, chemical, and nuclear weapons, as well as to exhibit “restraint” in the development and testing of their own ballistic missiles. It eventually became the Hague Code of Conduct Against Ballistic Missiles (HCOC).

  • International Convention on the Suppression of Acts of Nuclear Terrorism (NTC)

    The General Assembly adopted the Nuclear Terrorism Convention in April 2005. It opened for signature on 14 September 2005. The Convention addresses the unlawful possession or use of nuclear devices or materials by non-state actors. The Convention calls on states to develop a legal framework criminalizing offenses related to nuclear terrorism, as well as for international cooperation in nuclear terrorism investigations and prosecutions.

  • International Science and Technology Center (ISTC)

    Established in 1992, the Moscow-based ISTC serves as a clearinghouse for developing, approving, financing, and monitoring projects aimed at engaging weapon scientists and engineers from the Newly Independent States (NIS) in peaceful civilian science and technology activities. Through its projects, the ISTC contributes to ongoing efforts to stem the proliferation of weapons of mass destruction See entry for Science and Technology Center Ukraine.

  • Irradiate

    To expose to some form of radiation.

  • Isotope

    Any two or more forms of an element having identical or very closely related chemical properties and the same atomic number (the same number of protons in their nuclei), but different atomic weights or mass numbers (a different number of neutrons in their nuclei). Uranium-238 and uranium-235 are isotopes of uranium.


  • Joint Convention on the Safety of Spent Fuel Management (JC)

    The Joint Convention on the Safety of Spent Fuel Management opened for signature in 1997 and entered into force in 2001. The Convention aims to achieve and maintain a high level of safety in spent fuel and radioactive waste management; ensure that there are effective defenses against potential hazards during all stages of management of such materials; and prevent accidents with radiological consequences.

  • Joint Declaration on the Denuclearization of the Korean Peninsula

    On 20 January 1992, both North and South Korea signed the Joint Declaration on the Denuclearization of the Korean Peninsula, whereby both states agreed not to “test, produce, receive, possess, store, deploy or use nuclear weapons; to use nuclear energy only for peaceful purposes; and not to possess facilities for nuclear reprocessing or uranium enrichment.” The declaration entered into force on 19 February 1992. In order to implement the declaration, the two Koreas established the South-North Joint Nuclear Control Commission (JNCC). However, as the result of revelations about North Korea’s nuclear program and failure to reach agreement on the reciprocal inspection regime, implementation has been stalled since 1993.


  • Kiloton

    A term used to quantify the energy of a nuclear explosion that is equivalent to the explosion of 1,000 tons of trinitrotoluene (TNT) conventional explosive.

  • Korean Peninsula Energy Development Organization (KEDO)

    KEDO was a consortium established in early 1995 to implement the 1994 Agreed Framework between the DPRK and United States. Its primary responsibilities were to finance and supply the agreed to light-water reactor (LWR) project, to provide heavy oil to the DPRK to meet its interim heating and electricity-generation needs, and to provide for the implementation of other measures required under the terms of the Agreed Framework. Due to the DPRK’s nuclear weapons program in violation of the 1994 Agreed Framework, the KEDO project has been suspended since November 2003. See entry for Agreed Framework.


  • Lachrymator

    A lachrymator is a chemical agent that causes victims to produce tears from the eyes.  Also known as “tear gas,” although many are not gaseous, lachrymators were among the first chemical agents used in combat during World War I, and are still used as riot-control agents.  Examples include CS.

  • Lahore Declaration

    The Lahore Declaration is an agreement in which India and Pakistan pledged to “take immediate steps for reducing the risk of accidental or unauthorized use of nuclear weapons and discuss concepts and doctrines with a view to elaborating measures for confidence building in the nuclear and conventional fields, aimed at prevention of conflict.”

  • Latin American Nuclear-Weapon-Free Zone

    The Latin American Nuclear-Weapons-Free Zone, also called the Treaty of Tlatelolco, opened for signature in February 1967, created a nuclear-weapon-free zone in Latin America and the Caribbean. The Treaty of Tlatelolco was the first international agreement that aimed to exclude nuclear weapons from an inhabited region of the globe. The member states accept the application of International Atomic Energy Agency safeguards on all their nuclear activities. The treaty also establishes a regional organization, the Agency for the Prohibition of Nuclear Weapons in Latin America (OPANAL), to supervise treaty implementation and ensure compliance with its provisions.

  • Launch Registration Convention

    The Launch Registration Convention obliges parties to register all objects launched into earth’s orbit or outer-space with an appropriate national space agency, and entered into force in 1976. Under this Convention, information on the object launched into space, including the date and location of the launch and the function of the object in space is to be communicated to the UN Secretary General as soon as practicable.

  • Layered BMD system

    An approach to ballistic missile defense that consists of several “layers” of weapons intended to intercept an incoming ballistic missile at different phases of its flight. A layered approach would include a first layer (e.g., boost phase) of defense, with remaining targets passed on to succeeding layers (e.g., midcourse and terminal).

  • Lethal dose (radiation)

    The dose of radiation expected to cause death to an exposed population within 30 days to 50 percent of those exposed.

  • Lewisite (L)

    Lewisite is a blister agent that like mustard causes eye, skin, and airway irritation, but unlike mustard, acts immediately rather than with a delay. With significant exposure, lewisite can cause blindness. A colorless liquid, lewisite can be dispersed as a gas or a liquid.  Lewisite (L) has no known medical or other non-military uses.  Several countries, including Japan, the United States, and the Soviet Union, have produced and stockpiled lewisite.  Lewisite may have been used by Japan during World War II.

  • Light-water reactor

    A term used to describe reactors using ordinary water, where the hydrogen is hydrogen-1, as a coolant and moderator, including boiling water reactors (BWRs) and pressurized water reactors (PWRs), the most common types used in the United States.

  • Limited Test Ban Treaty

    Also known as the Partial Test Ban Treaty, the Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space and Under Water prohibits nuclear weapons tests “or any other nuclear explosion” in the atmosphere, in outer space, and under water. While the treaty does not ban tests underground, it does prohibit nuclear explosions in this environment if they cause “radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control” the explosions were conducted. The treaty is of unlimited duration.

  • Lisbon Protocol (START I Protocol)

    Refers to the protocol of the 1991 START I Treaty, which entered in force in December 1994 as the result of negotiations between the United States and the Soviet Union/Russian Federation, held between 1982 and 1993 to limit and reduce the numbers of strategic offensive nuclear weapons in each country’s nuclear arsenal. For additional information, see entry for Strategic Arms Reduction Talks and START I Treaty.

  • Low enriched uranium (LEU)

    Refers to uranium with a concentration of the isotope U-235 that is higher than that found in natural uranium but lower than 20% LEU (usually 3 to 5%). LEU is used as fuel for many nuclear reactor designs.

  • Low-yield Nuclear Earth Penetrator


  • Material protection, control, and accountability (MPC&A)

    An integrated system of physical protection, material accounting, and material control measures designed to deter, prevent, detect, and respond to unauthorized possession, use, or sabotage of nuclear materials. The U.S. Department of Energy’s MPC&A program was implemented in cooperation with the Russian Atomic Energy Ministry and other agencies to install and upgrade physical protection systems at the nuclear energy and weapons production facilities in the successor states of the former Soviet Union. See entry for Cooperative Threat Reduction.

  • Medical isotopes

    See entry for Radioisotopes.

  • Medium-enriched uranium (MEU) fuel

    Refers to uranium fuel with a concentration of the isotope U-235 between 20 and 35%. MEU is sometimes used to fuel research reactors.

  • Megaton (MT)

    The energy equivalent released by 1,000 kilotons (1,000,000 tons) of trinitrotoluene (TNT) explosive. Typically used as the unit of measurement to express the amount of energy released by a nuclear bomb.

  • Megatons to Megawatts program

    See entry for HEU deal.

  • Mendoza Agreement

    The Mendoza Agreement, signed in 1991 by Argentina, Brazil, and Chile, never entered into force. The Parties agreed not to develop, produce, acquire in any way, stockpile or retain, transfer directly or indirectly, or use chemical or biological weapons. Prior to the entry into force of the Chemical Weapons Convention (CWC), and in conformity with international law, the parties intended to establish in their respective countries the appropriate inspection mechanisms for those substances defined as precursors or chemical warfare agents.

  • Middle East Zone Free of Nuclear Weapons as well as Other Weapons of Mass Destruction

    The concept of an NWFZ in the Middle East was first introduced by Iran and Egypt in 1974. In April 1990, Egyptian President Hosni Mubarak proposed the establishment in the Middle East of a zone free of all types of weapons of mass destruction. In the “Resolution on the Middle East” adopted at the 1995 NPT Review Conference, the concept of a Middle East Zone Free of WMD was endorsed by all NPT state parties. The resolution calls on all regional states to join the NPT, place their nuclear facilities under IAEA safeguards, and work towards the establishment of a Middle East WMD-free zone. At the 2010 NPT Review Conference, in light of the minimal progress made since 1995, Arab states pushed for tangible steps toward the WMD-free zone. The result was a resolution calling for a meeting on the establishment of a Middle East WMD-free zone in 2012, to be attended by all states of the region. The meeting was subsequently postponed due to the parties’ failure to convene in 2012.

  • Middle Powers Initiative

    A group of eight international NGOs that work with middle power countries including Brazil, Egypt, Ireland, Mexico, New Zealand, South Africa, and Sweden for nuclear disarmament.

  • Mid phase (or midcourse phase)

    The second phase in the flight path of a ballistic missile, following the boost and preceding the terminal phase. The midcourse phase is the longest phase in the flight path of a ballistic missile. For an ICBM, it lasts about 20 minutes. Its relatively long duration has rendered the midcourse phase the preferred point for interception by ballistic missile defense systems.

  • Missile Technology Control Regime (MTCR)

    An informal arrangement established in April 1987 by an association of supplier states concerned about the proliferation of missile equipment and technology relevant to missiles that are capable of carrying a payload over 500 kilograms over a 300-kilometer range. Though originally intended to restrict the proliferation of nuclear-capable missiles, the regime has been expanded to restrict the spread of unmanned aerial vehicles.

  • Mixed Oxide (MOX) fuel

    A type of nuclear fuel used in light water reactors that consists of plutonium blended with uranium (natural, depleted or reprocessed). The MOX process also enables disposition of military plutonium, with the resulting fuel usable for energy generation.

  • Molybdenum-99 (Mo-99)

    See entry for Radioisotopes.

  • Monitoring

    See entry for Verification.

  • Multi-lateral

    Negotiations, agreements or treaties that are concluded among three or more parties, countries, etc.

  • Multiple Independently-targetable Reentry Vehicle (MIRV)

    An offensive ballistic missile system with multiple warheads, each of which can strike a separate target and can be launched by a single booster rocket.

  • Mustard (HD)

    Mustard is a blister agent, or vesicant.  The term mustard gas typically refers to sulfur mustard (HD), despite HD being neither a mustard nor a gas.  Sulfur mustard gained notoriety during World War I for causing more casualties than all of the other chemical agents combined.  Victims develop painful blisters on their skin, as well as lung and eye irritation leading to potential pulmonary edema and blindness.  However, mustard exposure is usually not fatal.  A liquid at room temperature, sulfur mustard has been delivered using artillery shells and aerial bombs.  HD is closely related to the nitrogen mustards (HN-1, HN-2, HN—3).

  • Mutual deterrence

    A condition of deterrence which exists between two adversaries. See Deterrence.

  • Mutually Assured Destruction (MAD)

    A term originating in the Cold War, which described the deterrence relationship between the United States and the Soviet Union beginning in the 1950s. MAD assumed that both sides possessed an assured second-strike capability such that a nuclear first-strike by either side would provide no strategic advantage—because both states would suffer unacceptably high damage in the ensuing nuclear war.


  • Nagasaki

    The second city in Japan on which an atomic bomb, “Fat Man,” was dropped on 9 August 1945 during WWII. More than 74,000 people were killed.

  • National Disaster Medical System (NDMS)

    The National Disaster Medical System (NDMS) is a section within the U.S. Department of Homeland Security, Federal Emergency Management Agency, Response Division, Operations Branch, and has the responsibility for managing and coordinating the federal medical response to major emergencies and federally declared disasters, including natural disasters, technological disasters, major transportation accidents, and acts of terrorism including Weapons of Mass Destruction.

  • National Institutes of Health (NIH)

    The National Institutes of Health (NIH) is the steward of medical and behavioral research for the United States. It is an agency under the U.S. Department of Health and Human Services.

  • National technical means (NTM)

    Satellites, aircraft, electronic, and seismic monitoring devices used to monitor the activities of other states, including treaty compliance and movement of troops and equipment. Some agreements include measures that explicitly prohibit tampering with other parties’ NTM. See entries for Transparency measures and Verification.

  • Negative security assurances

    A pledge by a nuclear weapon state that it will not use nuclear weapons against a non-nuclear weapon state. Some states have policies that allow for the use of nuclear weapons if attacked with other WMD by a non-nuclear weapon state. See entry for Positive security assurances.

  • Nerve agent

    A nerve agent is a chemical weapon that attacks the human nervous system, leading to uncontrolled nerve cell excitation and muscle contraction. Specifically, nerve agents block the enzyme cholinesterease, so acetylcholine builds up in the nerve junction and the neuron cannot return to the rest state. Nerve agents include the G-series nerve agents (soman, sarin, tabun, and GF) synthesized by Germany during and after World War II; the more toxic V-series nerve agents (VX, VE, VM, VG, VR) discovered by the United Kingdom during the 1950s; and the reportedly even more toxic Novichok agents, developed by the Soviet Union between 1960 and 1990.  The development of both the G-series and V-series nerve agents occurred alongside pesticide development.

  • Neutron

    An uncharged particle with a mass slightly greater than that of the proton, and found in the nucleus of every atom heavier than hydrogen-1.

  • New Agenda Coalition

    In June 1998, the foreign ministers of Brazil, Egypt, Ireland, Mexico, New Zealand, Slovenia, South Africa, and Sweden issued a statement calling for a new nuclear disarmament agenda. (Slovenia later withdrew from the NAC.) The NAC called for the five nuclear weapon states and the three nuclear-capable states to make an unequivocal commitment to nuclear disarmament and to begin multilateral negotiations that would lead to the elimination of nuclear weapons through a Nuclear Weapons Convention.

  • New START

    A treaty between the United States and Russia on further limitations and reductions of strategic offensive weapons, signed on 8 April 2010, which entered into force on 5 February 2011. Under the New START provisions, the two sides have to reduce the number of deployed strategic warheads and the number of deployed strategic delivery vehicles within seven years of the treaty’s entry into force. The treaty’s verification measures are based on the earlier verification system created under START I. New START supersedes the Moscow Treaty, and its duration is 10 years, with an option of extension for up to five years. See entry for Strategic Arms Reduction Treaty and Treaty of Moscow.

  • Nitrogen mustards

    Nitrogen mustards (HN-1, HN-2, and HN-3) are blister agents, or vesicants.  Victims develop painful blisters on the skin, as well as lung and eye irritation leading to potential pulmonary edema and blindness.  However, mustard exposure is usually not fatal.  All three nitrogen mustards are liquids at room temperature.  The three nitrogen mustards (HN-1, HN-2, and HN-3) are closely related in structure both to each other and to the sulfur mustard (HD), which has been more frequently used on the battlefield.  The United States and Germany stockpiled, but never used, nitrogen mustard during World War II.  Apart from their potential use as chemical warfare agents, nitrogen mustards can also be used to treat certain types of cancer.

  • No-First-Use

    A pledge on the part of a nuclear weapon state not to be the first party to use nuclear weapons in a conflict or crisis. No-first-use guarantees may be made in unilateral statements, bilateral or multilateral agreements, or as part of a treaty creating a nuclear-weapon-free zone.

  • Non-Aligned Movement (NAM)

    The Non-Aligned Movement was formed during the Cold War as an organization of states that did not seek to formally align themselves with either the United States or the Soviet Union, but sought to remain independent or neutral. NAM identifies the right of independent judgment, the struggle against imperialism and neo-colonialism, and the use of moderation in relations with all big powers as the three basic elements that have influenced its approach.

  • Non-nuclear weapon state (NNWS)

    Under the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), NNWS are states that had not detonated a nuclear device prior to 1 January 1967, and who agree in joining the NPT to refrain from pursuing nuclear weapons (that is, all state parties to the NPT other than the United States, the Soviet Union/Russia, the United Kingdom, France, and China).

  • Non-party

    A state or entity that is not a participant in an agreement, convention, or treaty.

  • Nonproliferation

    Measures to prevent the spread of biological, chemical, and/or nuclear weapons and their delivery systems. See entry for Proliferation.

  • Nonproliferation and Disarmament Initiative (NPDI)

    Founded by Australia, Canada, Chile, Germany, Japan, Mexico, the Netherlands, Poland, Turkey, and the United Arab Emirates in September 2010, the Nonproliferation and Disarmament Initiative (NPDI) is a ministerial-level group of states within the framework of the Nonproliferation Treaty focused on practical steps that will forward the consensus outcomes of the 2010 NPT Review Conference.

  • Nonproliferation Treaty (NPT)

    Signed in 1968, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is the most widely adhered-to international security agreement. The “three pillars” of the NPT are nuclear disarmament, nonproliferation, and peaceful uses of nuclear energy. Article VI of the NPT commits states possessing nuclear weapons to negotiate in good faith toward halting the arms race and the complete elimination of nuclear weapons. The Treaty stipulates that non-nuclear-weapon states will not seek to acquire nuclear weapons, and will accept International Atomic Energy Agency safeguards on their nuclear activities, while nuclear weapon states commit not to transfer nuclear weapons to other states. All states have a right to the peaceful use of nuclear energy, and should assist one another in its development. The NPT provides for conferences of member states to review treaty implementation at five-year intervals. Initially of a 25-year duration, the NPT was extended indefinitely in 1995.

  • Non-strategic nuclear weapons

    See entry for Tactical nuclear weapons

  • North American Aerospace (formerly Air) Defense Command (NORAD)

    The North American Aerospace (formerly Air) Defense Command (NORAD), established in 1957, is a bi-national air defense organization between the United States and Canada. Originally aimed at deterring threats from Soviet bombers and ICBMs, NORAD has expanded following the end of the Cold War and the attacks of 9/11, and now provides for aerospace warnings from aircraft, missiles, and space vehicles as well as risks emanating from the interior of North America. NORAD, headquartered at Peterson Air Force Base near Colorado Springs, Colorado, is broken down into three regional commands: the Alaskan NORAD Region (ANR), the Canadian NORAD Region (CANR), and the Continental U.S. NORAD Region (CONR).

  • North Atlantic Treaty Organization (NATO)

    The North Atlantic Treaty Organization is a military alliance that was formed in 1949 to help deter the Soviet Union from attacking Europe. The Alliance is based on the North Atlantic Treaty, which was signed in Washington on 4 April 1949. The treaty originally created an alliance of 10 European and two North American independent states, but today NATO has 28 members who have committed to maintaining and developing their defense capabilities, to consulting on issues of mutual security concern, and to the principle of collective self-defense. NATO is also engaged in out-of-area security operations, most notably in Afghanistan, where Alliance forces operate alongside other non-NATO countries as part of the International Security Assistance Force (ISAF).

  • Nuclear Cooperation (Section 123) Agreement

    Named after Section 123 of the U.S. Atomic Energy Act of 1954, this type of agreement governs U.S. peaceful nuclear cooperation with foreign states, and must be in place for certain types of transactions to occur.

  • Nuclear energy

    The energy liberated by a nuclear reaction (fission or fusion), or by radioactive decay.

  • Nuclear Energy Agency

    The Nuclear Energy Agency is a specialized agency within the Organization for Economic Cooperation and Development (OECD) that was established in 1958. The NEA’s objective is to assist member countries in maintaining and developing nuclear energy as a safe, environmentally acceptable, and economical energy source by serving as a forum where states can share information and experience and promote international cooperation.

  • (Nuclear) Forensics

    Refers to the process of investigating the origin of nuclear material, for example in nuclear materials trafficking cases.  For a related concept, see attribution.

  • Nuclear fuel cycle

    See entry for Fuel cycle.

  • Nuclear installation

    This term may be used to denote a nuclear power reactor, a nuclear research reactor, a critical facility, a conversion plant, a fabrication plant, a reprocessing plant, an isotope separation plant, a separate storage installation, or any other facility at which fresh or irradiated nuclear material or significant quantities of radioactive materials are present.

  • Nuclear Posture Review

    Under a mandate from the U.S. Congress, the Department of Defense regularly conducts a comprehensive Nuclear Posture Review to set forth the direction of U.S. nuclear weapons policies. To date, the United States has completed three Nuclear Posture Reviews (in 1994, 2001, and 2010).

  • Nuclear-powered ballistic missile submarines (SSBN)

  • Nuclear power plant

    A facility that generates electricity using a nuclear reactor as its heat source to provide steam to a turbine generator.

  • Nuclear reactor

    A vessel in which nuclear fission may be sustained and controlled in a chain nuclear reaction. The varieties are many, but all incorporate certain features, including: fissionable or fissile fuel; a moderating material (unless the reactor is operated on fast neutrons); a reflector to conserve escaping neutrons; provisions of removal of heat; measuring and controlling instruments; and protective devices.

  • Nuclear Security Summits

    A series of international summits that emerged out of U.S. President Barack Obama’s call in April 2009 to “secure all vulnerable nuclear material around the world within four years.” The summit process focuses on strengthening international cooperation to prevent nuclear terrorism, thwarting nuclear materials trafficking, and enhancing nuclear materials security.

  • Nuclear Suppliers Group (NSG)

    The NSG was established in 1975, and its members commit themselves to exporting sensitive nuclear technologies only to countries that adhere to strict non-proliferation standards.

  • Nuclear umbrella

    See entry for Extended deterrence

  • Nuclear (use) doctrine

    The fundamental principles by which a country’s political or military leaders guide their decision-making regarding the conditions for the use of nuclear weapons.

  • Nuclear weapon(s)

    A device that releases nuclear energy in an explosive manner as the result of nuclear chain reactions involving fission, or fission and fusion, of atomic nuclei. Such weapons are also sometimes referred to as atomic bombs (a fission-based weapon); or boosted fission weapons (a fission-based weapon deriving a slightly higher yield from a small fusion reaction); or hydrogen bombs/thermonuclear weapons (a weapon deriving a significant portion of its energy from fusion reactions).

  • Nuclear-Weapon-Free Southern Hemisphere and Adjacent Areas

    Current existing nuclear-weapon-free zones are all located in the Southern Hemisphere. Since 1996, the United Nations General Assembly has adopted a resolution calling for the creation of a Nuclear-Weapon-Free Southern Hemisphere and adjacent areas.

  • Nuclear-Weapon-Free Status of Mongolia

    The Mongolian government declared itself a single-state nuclear-weapon-free zone at the 47th session of the UN General Assembly in 1992. The 55th session of the UN General Assembly (2000) adopted Resolution 55/33S on “Mongolia’s international security and nuclear weapon free status.” Like other existing NWFZs, Mongolia’s single-state NWFZ is recognized internationally and contains verification and compliance mechanisms, although the only mechanisms that have been established are Mongolia’s comprehensive safeguards agreement with the IAEA, and the additional protocol to that agreement.

  • Nuclear-Weapon-Free Zone (NWFZ)

    A geographical area in which nuclear weapons may not legally be built, possessed, transferred, deployed, or tested.

  • Nuclear-Weapon-Free Zone Protocol

    Protocols to NWFZs provide for the obligations and rights of non-parties to the zones, and of the nuclear weapon states with reference to those states that are party to the NWFZs and the regions covered. Protocols may include assurances by the NWS not to use or threaten to use nuclear weapons against contracting parties within an NWFZ.

  • Nuclear-weapon states (NWS)

    As defined by Article IX, paragraph 3 of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), the five states that detonated a nuclear device prior to 1 January 1967 (China, France, the Soviet Union, the United Kingdom, and the United States). Coincidentally, these five states are also permanent members of the UN Security Council. States that acquired and/or tested nuclear weapons subsequently are not internationally recognized as nuclear-weapon states.

  • Nucleus

    The central, positively charged region of an atom. Except for the nucleus of ordinary hydrogen (or hydrogen-1), which has only a proton, all atomic nuclei contain both protons and neutrons. The number of protons determines the total positive charge or atomic number. This number is the same for all the atomic nuclei of a given chemical element. The total number of neutrons and protons is called the mass number or atomic mass number.

  • Nunn-Lugar program


  • Offensive (research, weapon)

    Meant for use in instigating an attack, as opposed to defending against an attack.

  • Office of Emergency Preparedness (OEP)

  • Office of Public Health Preparedness and Response (OPHP)


    The Agency for the Prohibition of Nuclear Weapons in Latin America and the Caribbean (OPANAL) is an intergovernmental agency created by the Treaty of Tlatelolco to ensure that the obligations of the Treaty are met. Since 1998, all 33 states in Latin America and the Caribbean have been Members of OPANAL.

  • Organization for Security and Cooperation in Europe (OSCE)

    The OSCE was created in 1975 as the Conference on Security and Cooperation in Europe (CSCE) as part of the Helsinki negotiations between the United States and the Soviet Union. The OSCE is composed of most NATO and former Warsaw Pact nations, including the United States, Canada, and Russia. Its purpose is to guarantee European security and human rights.

  • Organization for the Prohibition of Chemical Weapons (OPCW)

    Based in The Hague, the Netherlands, the OPCW is responsible for implementing the Chemical Weapons Convention (CWC). All countries ratifying the CWC become state parties to the CWC, and make up the membership of the OPCW. The OPCW meets annually, and in special sessions when necessary.

  • Organization of African Unity (OAU)/African Union

    The OAU was established to promote the unity of African countries in 1963. At the first summit of the Organization of African Unity in Cairo in July 1964, the African Heads of State or Government called for a treaty declaring Africa free of nuclear weapons. The OAU was transformed into the African Union on 26 May 2001. See entry for the Treaty of Pelindaba.

  • Outer Space Treaty

    The Treaty on Principles Governing the Activities of States in the Exploration and use of Outer Space, Including the Moon and other Celestial Bodies prohibits the placement of Weapons of Mass Destruction in orbit around the earth, on the moon or any other celestial body, or otherwise in outer space. The treaty also stipulates that the exploration and use of outer space be carried out for the benefit and in the interest of all countries, and that the moon and other celestial bodies are to be used exclusively for peaceful purposes. It was opened for signature on 27 January 1967, and entered into force on 10 October 1967.


  • P-5

    The five permanent members of the United Nations Security Council: China, France, the Russian Federation, the United Kingdom, and the United States.

  • Partial Test Ban Treaty (PTBT)

    Also known as the Limited Test Ban Treaty (LTBT), the Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space and Under Water prohibits nuclear weapons tests “or any other nuclear explosion” in the atmosphere, in outer space, and under water. While the treaty does not ban tests underground, it does prohibit nuclear explosions in this environment if they cause “radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control” the explosions were conducted. The treaty is of unlimited duration.

  • Party

    A person, group, or state that agrees to abide by the requirements of an agreement or treaty.

  • Passive defenses

    Passive defenses are measures intended to reduce the consequences of a (WMD) attack (e.g., the use of shelters during a nuclear attack, the use of protective clothing to reduce the impact of a chemical weapons attack, or the use of inoculations to reduce the impact of a biological weapons attack). See entry for Active Defenses.

  • Pathogen

    A microorganism capable of causing disease.

  • Patriot (PAC) Program

    The Patriot, first deployed in 1984, is the U.S. Army’s air and missile defense system. The Patriot Advanced Capability (PAC) is the anti-theater ballistic missile defense component of the Patriot system.

  • Peaceful Nuclear Explosion (PNE)

    PNEs are nuclear explosions carried out for non-military purposes, such as the construction of harbors or canals. PNEs are technically indistinguishable from nuclear explosions of a military nature. Although Article V of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) allows for PNEs, no significant peaceful benefits of these explosions (that outweigh the drawbacks), have been discovered. In the Final Document of the 2000 NPT Review Conference, the state parties agreed that Article V of the NPT is to be interpreted in light of the Comprehensive Nuclear Test Ban Treaty, which will ban all nuclear explosions, including PNEs, once it enters into force.

  • Penetration Aid (PENAIDS)

    A countermeasure incorporated in an offensive ballistic missile to increase the chances that the missile will penetrate a target’s defenses.

  • Peaceful Nuclear Explosion Treaty (PNET)

    The Treaty between the United States and the USSR on Underground Nuclear Explosions for Peaceful Purposes was signed in May 1976. The agreement governs all nuclear explosions conducted outside of nuclear test sites specifically named in the Threshold Test Ban Treaty. The PNET entered into force in December 1990. Many of its provisions were superseded by the Comprehensive Nuclear Test Ban Treaty, which bans all nuclear explosions. See entries for Peaceful Nuclear Explosion and Comprehensive Nuclear Test Ban Treaty.

  • Persistent

    In the context of chemical agents, the ability to remain in liquid form without evaporating for some length of time at normal temperatures and pressures.

  • Phased, Adaptive Approach (PAA)

    An architecture for missile defense in Europe proposed by the U.S. Obama administration for countering the perceived growing ballistic missile threat from Iran.  The phased, adaptive approach, as envisioned, would use land-and-sea-based SM-3 interceptors and sophisticated sensors deployed in southern and northern Europe.  These systems could potentially provide Europe and the U.S. homeland with a mechanism for defense against the full range of Iranian ballistic missiles that can adapt appropriately as the threat evolves.  The approach would deploy this technology in phases as it continues to mature from 2011 to 2020.

  • Phosgene (CG)

    A choking agent, phosgene gas causes damage to the respiratory system leading to fluid build-up in the lungs.  Phosgene also causes coughing, throat and eye irritation, tearing, and blurred vision.  A gas at room temperature, phosgene can be delivered as a pressurized liquid that quickly converts to gas. Germany and France used phosgene during World War I; the United Kingdom, the United States, and Russia also produced military phosgene.  Phosgene caused over 80% of the deaths from chemical gas during World War I.

  • Phosgene oxime (CX)

    Although sometimes described as a vesicant, phosgene oxime (CX) does not in fact produce vesicles, and would be more appropriately classified as a urticant or nettle agent.  Although phosgene is among the least studied chemical weapons, it is one of the fastest working and produces immediate and severe skin and eye pain.  Tissue damage and death, as well as build-up of fluid in the lungs, follow.  Phosgene oxime can be delivered as a thermal fog or in liquid form, and imparts a disagreeable odor.

  • Plague

    The disease caused by the bacterium Yersinia pestis. There are three forms of plague: bubonic plague, pneumonic plague, and septicemic plague.  Bubonic plague refers to infection of the lymph nodes by Y. pestis, causing black sores or “buboes,” pneumonic plague refers to infection of the lungs, and septicemic plague refers to infection of the bloodstream.  Although no longer a serious public health hazard in the developed world, the bacterium can spread from person-to-person in aerosolized form, and has been investigated as a biological weapon by Japan and the Soviet Union.

  • Plutonium (Pu)

    A transuranic element with atomic number 94, produced when uranium is irradiated in a reactor. It is used primarily in nuclear weapons and, along with uranium, in mixed-oxide (MOX) fuel. Plutonium-239, a fissile isotope, is the most suitable isotope for use in nuclear weapons.

  • Positive security assurances

    A guarantee given by a nuclear weapon state to a non-nuclear weapon state for assistance if the latter is targeted or threatened with nuclear weapons.  See entry for Negative security assurances.

  • Prague Speech

    Refers to the speech given by U.S. President Barack Obama in April 2009 at Hradcany Square, Prague, the Czech Republic. In the speech, Obama stated “America’s commitment to seek the peace and security of a world without nuclear weapons.” He noted that “the United States will take concrete steps towards a world without nuclear weapons.” The Prague speech served as the framework for the 2010 Nuclear Posture Review and subsequent U.S. arms control efforts.

  • Preemptive military action

    An attack launched to preempt expected aggression by an enemy. In the context of WMD issues, this would involve striking WMD arsenals or facilities to eliminate them before broader hostilities ensue.

  • Preparatory Commission of the CTBTO

    The Preparatory Commission is an international organization tasked with building, certifying and operating the infrastructure for the detection and investigation of nuclear tests, preparing the regulations for the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), and leading activities that will facilitate the early entry into force of the Comprehensive Nuclear Test Ban Treaty (CTBT). The organization will cease operations following the entry into force of the CTBT.  For additional information, see the CTBTO.

  • Presidential Nuclear Initiatives (PNI)

    A series of initiatives announced in 1991 by U.S. President George H. W. Bush and Soviet General Secretary Mikhail Gorbachev, declaring that their two countries would reduce tactical nuclear weapons arsenals and associated delivery systems.

  • Pressurized water reactor

    A reactor in which the water which flows through the core is isolated from the turbine, unlike in a boiling water reactor. The primary water, contained in one loop, travels through an additional heat exchanger (or steam generator) and produces steam in the secondary loop which, in turn, powers the turbine. See entry for Boiling water reactor.

  • Proliferation (of weapons of mass destruction)

    The spread of biological, chemical, and/or nuclear weapons, and their delivery systems. Horizontal proliferation refers to the spread of WMD to states that have not previously possessed them. Vertical proliferation refers to an increase in the quantity or capabilities of existing WMD arsenals within a state.

  • Proliferation Security Initiative (PSI)

    Announced by U.S. President George W. Bush in May 2003, PSI is a U.S.- led effort to prevent the proliferation of WMD, their delivery systems, and related materials through the use of information sharing and coordination of diplomatic and military efforts. Members of the initiative share a set of 13 common principles, which guide PSI efforts.

  • Proposed Nuclear Weapons Convention

    A proposed international treaty that would establish provisions that prohibit the development, testing, production, stockpiling, transfer, use and threat of use of nuclear weapons, as well as provide for their elimination, similar to the Biological and Toxin Weapons Convention and the Chemical Weapons Convention.

  • Protocol

    A negotiated document often intended to supplement a treaty or agreement, stipulating specific actions that should be taken to fulfill the terms of the agreement, or modifying the agreement.

  • Proton

    A particle with a positive electric charge located in the nucleus of an atom.

  • Pugwash Conference

    Established in 1957, the Pugwash Conference is an annual meeting of scholars and public figures who discuss and debate arms control and security issues in an unofficial manner, rather than as official representatives of their governments or international organizations.


  • Quadrennial Defense Review (QDR)

    The QDR outlines the U.S. Defense Department’s strategy for defending the United States and the resources needed to do so. Its release coincides with presidential elections.


  • Radiation (Ionizing)

    Radiation that has sufficient energy to remove electrons from substances that it passes through, forming ions. May include alpha particles, beta particles, gamma rays, x-rays, neutrons, high-speed electrons, high-speed protons, and other particles capable of producing ions.

  • Radiation exposure device (RED)

    Employs radioactive material to expose passersby to potentially harmful levels of radiation.

  • Radiation shielding

    Any material that absorbs radiation, which may be used to protect personnel or materials from the effects of ionizing radiation.

  • Radiation source

    Usually a sealed source of radiation used in teletherapy and industrial radiography, as a power source for batteries, or in various types of industrial gauges. Machines, such as accelerators, radioisotope generators, and natural radionuclides may be considered sources. Some sources are also used for research and experimentation.

  • Radiation syndrome (also called radiation sickness)

    The complex of symptoms resulting from excessive exposure of the human body to acute ionizing radiation. The earliest symptoms may include nausea, fatigue, vomiting, and diarrhea, which may be followed by loss of hair, hemorrhage, inflammation of the mouth and throat, and a general loss of energy. In severe cases, where the radiation has been approximately 1,000 rad (acute dose) or more, death may occur within two to four weeks. Those who survive six weeks after the receipt of a single large dose of radiation to the whole body may generally be expected to recover. Over the long-term, there are also stochastic health effects from radiation exposure (in contrast to acute effects), meaning an increased probability of cancers and other negative effects on a person’s health.

  • Radioactive decay

    The spontaneous emission of energy and/or particles from the nucleus of a radioactive atom.  This is most often in the form of either alpha or beta particles, gamma radiation, or spontaneous fission where the nucleus undergoes fission without the bombardment of a particle or photon.  Each radioactive isotope has an associated half-life, and the amount of radioactive material decreases over time as the material decays.

  • Radioactive waste

    Materials which are radioactive and for which there is no further use.

  • Radioactivity

    The spontaneous emission of radiation, generally alpha or beta particles, often accompanied by gamma rays, from the nucleus of an unstable isotope.

  • Radiocarbon dating

    A technique for estimating the age of an object by measuring the amounts of various radioisotopes in it.

  • Radioisotope

    An unstable isotope of an element that decays or disintegrates spontaneously, emitting energy (radiation). Approximately 5,000 natural and artificial radioisotopes have been identified. Some radioisotopes, such as Molybdenum-99, are used for medical applications, such as diagnostics. These isotopes are created by the irradiation of targets in research reactors.

  • Radiological dispersal device (RDD)

    Any device, other than a nuclear explosive device, designed to spread radioactive material.

  • Radiological terrorism

    Terrorist acts intended to release harmful radiation, through sabotage of a nuclear facility or the detonation of a radiological dispersal device (RDD).  See radiological dispersal device.

  • Rapacki Plan

    The Rapacki Plan was a proposal to establish a zone free of nuclear weapons in Central and Eastern Europe named after the Polish foreign minister, Adam Rapacki, in 1958. Although the plan was not negotiated seriously due to the Cold War security environment, several elements of the Rapacki Plan were later adopted as guidelines for the establishment of denuclearized zones.

  • Ratification

    The implementation of the formal process established by a country to legally bind its government to a treaty, such as approval by a parliament. In the United States, treaty ratification requires approval by the president after he or she has received the advice and consent of two-thirds of the Senate. Following ratification, a country submits the requisite legal instrument to the treaty’s depository governments.  Procedures to ratify a treaty follow its signature.

    See entries for Entry into force and Signature.

  • Re-activation

    The reversal of measures to deactivate or de-alert missiles, or the return of former military facilities or equipment to military use. In the case of missile re-activation, warheads are removed from storage facilities and redeployed on missiles.

  • Reentry phase

    The portion of the trajectory of a ballistic missile or space vehicle when the vehicle reenters the earth’s atmosphere.

  • Reentry Vehicle (RV)

    A nuclear warhead on a ballistic missile specially designed to reenter the earth’s atmosphere in the terminal portion of the missile’s trajectory.

  • Regime

    An institution in which rules or practices (sometimes formalized in a treaty or convention), are generally accepted by a group of states to facilitate cooperation in an otherwise anarchic international system.

  • Reliable Replacement Warhead (RRW)

    The Reliable Replacement Warhead (RRW) program was proposed by the U.S. National Nuclear Security Administration and funded by Congress from 2005 to 2010. The program aimed to research and develop new components to replace parts of existing warheads without utilizing nuclear testing, but failed due to immense political controversy.

  • Repatriation

    In the context of threat reduction, repatriation refers to the process of returning nuclear materials (e.g., fresh or spent HEU fuel), to the state that originally exported them.

  • Reprocessing

    The chemical treatment of spent nuclear fuel to separate the remaining usable plutonium and uranium for re-fabrication into fuel, or alternatively, to extract the plutonium for use in nuclear weapons.

  • RERTR program

    The Reduced Enrichment for Research and Test Reactors (RERTR) program, conceived in the wake of India’s first nuclear test in 1974, is a U.S.-led effort to reduce the use of HEU in civil research reactors exported during the Atoms for Peace Program. Under the program, the United States has worked to develop new LEU fuels, and to convert research reactors and critical assemblies to these fuels at home and abroad. The RERTR program was folded into the Global Threat Reduction Initiative (GTRI) in 2004. See entry for the Global Threat Reduction Initiative.

  • Research reactor

    A small fission reactor designed to produce neutrons for a variety of purposes, including scientific research, training, and medical isotope production. Significantly less powerful than commercial power reactors, research reactors use smaller amounts of uranium for neutron production. Most of the research reactors that are powered by HEU have been undergoing conversion to LEU, initially as part of the RERTR program and subsequently as part of the Global Threat Reduction Initiative. See entries for Global Threat Reduction Initiative and the RERTR program.

  • Resilience

    Refers to economic and psychological endurance and adaptation in the wake of an attack or a terrorist act.

  • Rio Group

    The Rio Group is an international organization consisting of 23 Latin American and Caribbean countries created in 1986 in Rio de Janeiro, Brazil. The Rio Group does not have a secretariat or permanent body, and is governed by yearly summits of the heads of state. Originally acting as an alternative to the Organization of American States, the Rio Group works to expand and systematize political cooperation among the member states, examine international issues which may be of interest and coordinate common positions on these issues, and explore new fields of cooperation to enhance development.

  • Riot-control agent

    A riot-control agent, or RCA, is a chemical weapon of relative low-toxicity that produces highly irritating effects upon contact.  Although designed to be non-lethal, RCAs can produce death in high concentrations or against particularly vulnerable victims. The Chemical Weapons Convention allows the use of RCAs for domestic law enforcement.  Most commonly, RCAs are lachrymators such as tear gas.

  • Robust Nuclear Earth Penetrator (RNEP)

    A U.S. program during the George W. Bush administration that envisioned the development of a “bunker buster” nuclear weapon that would penetrate deep into the earth prior to detonation in order to destroy deeply buried and hardened targets. The RNEP was never built.

  • “Rogue” states

    See entry for States of concern.


  • Safeguards

    A system of accounting, containment, surveillance, and inspections aimed at verifying that states are in compliance with their treaty obligations concerning the supply, manufacture, and use of civil nuclear materials. The term frequently refers to the safeguards systems maintained by the International Atomic Energy Agency (IAEA) in all nuclear facilities in non-nuclear weapon state parties to the NPT. IAEA safeguards aim to detect the diversion of a significant quantity of nuclear material in a timely manner. However, the term can also refer to, for example, a bilateral agreement between a supplier state and an importer state on the use of a certain nuclear technology.

    See entries for Full-scope safeguards, information-driven safeguards, Information Circular 66, and Information Circular 153.

  • Sanctions

    Punitive measures, for example economic in nature, implemented in response to a state’s violation of its international obligations.

  • Sarin (GB)

    A nerve agent, sarin causes uncontrollable nerve cell excitation and muscle contraction.  Ultimately, sarin victims suffer death by suffocation. As with other nerve agents, sarin can cause death within minutes.  Sarin vapor is about ten times less toxic than VX vapor, but 25 times more toxic than hydrogen cyanide.  Discovered while attempting to produce more potent pesticides, sarin is the most toxic of the four G-series nerve agents developed by Germany during World War II.  Germany never used sarin during the war.  However, Iraq may have used sarin during the Iran-Iraq War, and Aum Shinrikyo is known to have used low-quality sarin during its attack on the Tokyo subway system that killed 12 people and injured hundreds.

  • Science and Technology Center Ukraine

    Established in 1993 by the European Union, the United States, Canada, and Ukraine, the STCU supports research and development activities that engage weapons scientists and engineers from Ukraine, Georgia, and Uzbekistan in peaceful civilian science and technology activities. See entry for International Science and Technology Center (ISTC).

  • Scud

    Scud is the designation for a series of short-range ballistic missiles developed by the Soviet Union in the 1950s and transferred to many other countries. Most theater ballistic missiles developed and deployed in countries of proliferation concern, for example Iran and North Korea, are based on the Scud design.

  • Seabed Treaty

    The Treaty on the Prohibition of the Emplacement of Nuclear Weapons and other Weapons of Mass Destruction on the Seabed and the Ocean Floor and in the Subsoil Thereof prohibits the placement of nuclear weapons or any other weapons of mass destruction on the seabed, the ocean floor, and in the subsoil of the ocean floor beyond a signatory’s 12-miles coastal zone. Opened for signature on 11 February 1971, it entered into force on 18 May 1972.

  • Sea-Launched Cruise Missile (SLCM)

    Refers to cruise missiles with conventional or nuclear payloads that are launched from submarines.

  • Sealed source

    Any radioactive material encased in a capsule designed to prevent leakage or escape of the material.

  • Second Line of Defense (NNSA)

    This DOE NNSA program works to prevent illicit trafficking in nuclear and radiological materials by securing international land borders, seaports and airports that may be used as smuggling routes for materials needed for a nuclear device or a radiological dispersal device. SLD has two main parts, the Core Program and the Megaports Initiative.

  • Section 123 Agreement

  • Self-protection (of nuclear fuel)

    Fuel is considered “self protecting” if it is sufficiently radioactive that those who might seek to divert it would not be able to handle it directly without suffering acute radiation exposure.

  • Signature

    The signing of an agreement by a senior or designated representative of a country, which indicates that the country accepts the treaty and commits, until the completion of the internal ratification process, not to take any actions that would undermine its purposes, according to the Vienna Convention on the Law of Treaties. See entries for entry into force, Ratification.

  • Silo

    Hardened underground facility for housing and launching a ballistic missile.

  • Single Integrated Operational Plan (SIOP)

    The nuclear war plan for an integrated response to a nuclear attack on the United States. In 1960, the U.S. Joint Strategic Target Planning Staff completed the SIOP 62. Since then, a version of the SIOP war plan has dictated how U.S. nuclear forces would be used in a conflict. With guidance from the President, the Secretary of Defense, and the Joint Chiefs of Staff, the Staff of the U.S. Strategic Command (STRATCOM) works out the details of the SIOP. STRATCOM designs and maintains the list of targets for nuclear attacks. The Pentagon formally changed the name of the SIOP in 2003, to OPLAN 8044 Revision (FY).

  • Soman (GD)

    A nerve agent, soman causes uncontrollable nerve excitation and muscle contraction.  Ultimately, soman victims suffer death by suffocation.  As with other nerve agents, soman can cause death within minutes. One of the G-series nerve agents, soman was developed as an insecticide in Germany in 1944, and may have been used by Iraq during the Iran-Iraq War.

  • South Asian Association for Regional Cooperation (SAARC)

    The South Asian Association for Regional Cooperation (SAARC) is an organization of South Asian states focusing on 11 different areas of cooperation. Regional meetings occur annually among heads of state, and biannually among foreign secretaries.

  • Southeast Asian Nuclear-Weapon-Free-Zone

    The Treaty on the Southeast Asian Nuclear-Weapon-Free-Zone (SEANWFZ) prohibits the development, manufacture, acquisition, or testing of nuclear weapons anywhere within the region. It also prohibits the transport of nuclear weapons through the region, as well as the dumping at sea, discharging into the atmosphere, or burying on land of any radioactive material or waste. In addition, the treaty requires all parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities.

  • South Pacific Nuclear-Weapon-Free-Zone

    The Treaty on the South Pacific Nuclear-Weapon-Free Zone (SPNWFZ) prohibits the testing, manufacturing, acquiring, and stationing of nuclear explosive devices on any member’s territory. The treaty also prohibits the dumping of radioactive wastes into the sea. In addition, the treaty required all parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities.

  • Space Launch Vehicle (SLV)

    A rocket used to carry a payload, such as a satellite, from Earth into outer space. SLVs are of proliferation concern because their development requires a sophisticated understanding of the same technologies used in the development of long-range ballistic missiles. Some states (e.g., Iran), may have developed space launch vehicle programs in order to augment their ballistic missile capabilities.

  • Special nuclear material

    Defined in the U.S. Atomic Energy Act of 1954 as plutonium, uranium-233, or uranium enriched in the isotope uranium-235.

  • Spent nuclear fuel

    Irradiated nuclear fuel. Once irradiated, nuclear fuel is highly radioactive and extremely physically hot, necessitating special remote handling. Fuel is considered “self protecting” if it is sufficiently radioactive that those who might seek to divert it would not be able to handle it directly without suffering acute radiation exposure.

  • SSBN

    Ship, Submersible, Ballistic, Nuclear: A hull classification for a submarine capable of launching a ballistic missile. The “N”, or nuclear, refers to the ship’s propulsion system. SSBN’s are generally reserved for strategic vessels, as most submarine launched ballistic missiles carry nuclear payloads. A non-strategic vessel carries the designation SSN, or attack submarine.

  • SSGN

    Ship, Submersible, Guided, Nuclear: A hull classification for a submarine that carries guided cruise missiles. The “N”, or nuclear, refers to the ship’s propulsion system. Also known as attack submarines, SSGNs serve a conventional military support role and are often used for special forces transportation.

  • States of concern

    The term used to denote states perceived as hostile to the United States and its allies and which are developing or possess WMD. The term “states of concern” has replaced the term “rogue” states due to its political sensitivity. The latter term was originally used during the Clinton Administration. Though the U.S. Department of State has discouraged use of the term “rogue states,” it is still used by some U.S. officials, especially in reference to North Korea, Syria, and Iran.

  • Stockpile Life Extension Program (LEP)

    The LEP is an NNSA program aimed at extending the lifetime and guaranteeing the reliability of the U.S. nuclear stockpile.

  • Stockpile Stewardship Program

    NNSA programs associated with research, design, development, and testing of U.S. nuclear weapons, and the assessment and certification of their safety and reliability. These activities include the Stockpile Life Extension Program (LEP).

  • Strategic Arms Limitations Talks (SALT I & II)

    A series of discussions between the Soviet Union and the United States aimed at limiting missile systems and other strategic armaments. The first round of talks (SALT I) was held from 1969 to 1972, and concluded with the 20 May 1971 signing of the Anti-Ballistic Missile (ABM) Treaty and the Interim Agreement limiting strategic offensive arms. SALT II was held from 1972 to 1979. The SALT II Treaty was signed on 18 June 1979, but was not ratified by either country, although both committed to abiding by its limits.

  • Strategic Arms Reduction Treaty (START I, II, & III)

    Refers to negotiations between the United States and the Soviet Union/Russian Federation, held between 1982 and 1993 to limit and reduce the numbers of strategic offensive nuclear weapons in each country’s nuclear arsenal. The talks culminated in the 1991 START I Treaty, which entered into force in December 1994, and the 1993 START II Treaty. Although START II was ratified by the two countries, it never entered into force. In 1997, U.S. President Bill Clinton and Russian President Boris Yeltsin discussed the possibility of a START III treaty to make further weapons reductions, but negotiations resulted in a stalemate. Following the U.S. withdrawal from the Anti-Ballistic Missile Treaty (ABM) in 2002, Russia declared START II void. START I expired on 5 December 2009, and was followed by the New START treaty. See entries for New START and the Trilateral Statement.

  • Strategic Bomber

    A long-range aircraft designed to drop large amounts of explosive power—either conventional or nuclear—on enemy territory.

  • Strategic Defense Initiative (SDI)

    Launched by U.S. President Ronald Reagan in March 1983, the SDI was aimed at studying the feasibility of research and development of defensive measures against ballistic missiles, with the ultimate goal of establishing a national missile defense system that would protect the United States from ballistic missile attacks. See entries for Anti-Ballistic Missile Treaty, Ballistic Missile.

  • Strategic nuclear warhead

    A high-yield nuclear warhead placed on a long-range delivery system, such as a land-based intercontinental ballistic missile (ICBMs), a submarine-launched ballistic missile (SLBMs), or a strategic bomber.

  • Strategic Offensive Reductions Treaty (SORT)

    Russian President Vladimir Putin and U.S. President George W. Bush signed the Strategic Offensive Reductions Treaty, also called the Treaty of Moscow on 24 May 2002. The treaty stated that both the United States and Russia would reduce the numbers of their deployed nuclear warheads to between 1700 and 2200 within the next ten years. It established a Bilateral Implementation Commission, scheduled to meet at least twice a year, to establish procedures to verify and assist reductions. The treaty was rendered obsolete by the signing of the New START treaty in 2010.

  • Sub-critical mass

    A mass of fissionable material that is smaller than that required for a self-sustaining chain reaction.

  • Sub-critical test

    A test that is used to gather information about nuclear warhead design and performance. Although a sub-critical test uses some fissile materials, it does not produce a nuclear explosion or result in the release of radioactivity.

  • Submarine-launched ballistic missile (SLBM)

    A ballistic missile that is carried on and launched from a submarine.

  • Subnational group

    A distinct group of people acting independently of the nation as a whole and operating without state supervision. The term often refers to groups acting against the government of the state, such as guerrillas or terrorists.

  • Supercritical mass

    A mass of fissionable material that is larger than the amount needed to sustain a fission chain reaction. The detonation mechanism of a nuclear weapon relies on the creation of a supercritical mass of fissile material.

  • Supportive treatment

    Medical treatment that concentrates on alleviating the symptoms of an illness rather than addressing its cause.


  • Tabun (GA)

    A nerve agent, tabun was the first of the nerve agents discovered in Germany in the 1930s.  One of the G-series nerve agents, Nazi Germany produced large quantities of tabun but never used it on the battlefield.  Tabun causes uncontrollable nerve excitation and muscle contraction.  Ultimately, tabun victims suffer death by suffocation.  As with other nerve agents, tabun can cause death within minutes. Tabun is much less volatile than sarin (GB) and soman (GD), but also less toxic.

  • Tactical nuclear weapons

    Short-range nuclear weapons, such as artillery shells, bombs, and short-range missiles, deployed for use in battlefield operations.

  • Tashkent Agreement

    See entry for Conventional Armed Forces in Europe (CFE) Treaty.

  • Terminal-phase

    The third and final phase of the flight path of a ballistic missile. Refers to the trajectory of the warhead, now decoupled from the missile, as it re-enters the earth’s atmosphere and proceeds to its target.

  • Theater ballistic missile

     Short- or medium-range ballistic missiles with a range between 300km and 3,500 km.

  • Theater High Altitude Air Defense (THAAD)

    The U.S. Army’s air defense program designed to provide extended defense, and to engage an incoming missile at ranges of up to several hundred kilometers. THAAD deploys a hit-to-kill interceptor equipped with an infrared seeker. The interception is intended to occur outside the earth’s atmosphere, or high in the atmosphere.

  • Theater missile defense (TMD)

    A system of missile interceptors designed to intercept ballistic missiles launched from a certain region or area.

  • Thermonuclear weapon

    A nuclear weapon in which the fusion of light nuclei, such as deuterium and tritium, leads to a significantly higher explosive yield than in a regular fission weapon. Thermonuclear weapons are sometimes referred to as staged weapons, because the initial fission reaction (the first stage) creates the condition under which the thermonuclear reaction can occur (the second stage).  Also archaically referred to as a hydrogen bomb.

  • Thirteen Practical Steps

    The Thirteen Practical Steps toward nuclear disarmament were adopted as part of the Final Document at the 2000 NPT Review Conference. The steps outlined ways in which Article VI, the nuclear disarmament provision of the NPT, could be implemented.

  • Threshold Test Ban Treaty (TTBT)

    Officially called the “Treaty on the Limitation of Underground Nuclear Weapon Tests,” this treaty between the United States and the Soviet Union prohibited underground nuclear weapon tests having a yield exceeding 150 kilotons. The treaty was signed on 3 July 1974, and entered into force on 11 December 1990.

  • Throw-weight

    Refers to the total weight of the warhead(s), any penetration aids, and guidance systems a missile is capable of delivering to a target, and is a measure of the destructive potential of a ballistic missile. Some arms control treaties classify different missile types based on throw-weight.

  • Tokyo Forum

    The Tokyo Forum for Nuclear Nonproliferation and Disarmament was sponsored by the Japanese government in 1999. Responding to India and Pakistan’s nuclear weapon tests and sending a strong signal of Japan’s consistent political will to support the NPT regime, the Forum issued a final report titled “Facing Nuclear Dangers: An Action Plan for the 21st Century,” containing a comprehensive nuclear disarmament and nonproliferation agenda.

  • Toxic Industrial Chemical

    A chemical used for legitimate medical or industrial purposes that is also highly toxic.  Toxic industrial chemicals are produced in large quantities and used throughout the world.  An accident or act of sabotage involving toxic industrial chemicals, particularly where they are being stored or transported in large quantities, could release toxic chemicals over vast areas and cause many casualties.

  • Toxin

    A poison formed as a specific secretion product in the metabolism of a vegetable or animal organism, as distinguished from inorganic poisons. Such poisons can also be manufactured by synthetic processes.

  • Transparency measures

    Measures designed to increase confidence in a state’s compliance with treaty obligations, or to provide warnings of noncompliance through access to information or the exchange of information, access to facilities, and other cooperative measures. See entries for Confidence and Security Building Measures, National Technical Means, and Verification.

  • Treaty Between the United States of America and the Russian Federation on Strategic Offensive Reductions (SORT)

    Also known as the Treaty of Moscow, SORT was an operationally deployed offensive strategic arms reduction treaty between the United States of America and the Russian Federation. The Treaty was in force from June 2004 until February 2011, when it was superseded by the New START treaty. The Treaty stipulated that the United States and Russia both had to reduce their strategic arsenals to between 1,700 and 2,200 warheads each, but did not stipulate the destruction of delivery vehicles or the warheads.

  • Treaty of Bangkok

    The Treaty on the Southeast Asian Nuclear-Weapon-Free-Zone prohibits the development, manufacture, acquisition, or testing of nuclear weapons anywhere within the region. It also prohibits the transport of nuclear weapons through the region, as well as the dumping at sea, discharging into the atmosphere, or burying on land of any radioactive material or waste. In addition, the treaty requires all parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities.

  • Treaty of Moscow

    Also known as the Strategic Arms Reduction Treaty (SORT), Russian President Vladimir Putin and U.S. President George W. Bush signed the Treaty of Moscow on 24 May 2002. The treaty stated that both the United States and Russia would reduce the numbers of their deployed nuclear warheads to between 1700 and 2200 within the next ten years. It established a Bilateral Implementation Commission, scheduled to meet at least twice a year, to establish procedures to verify and assist reductions. The treaty was rendered obsolete by the signing of the New START treaty in 2010.

  • Treaty of Pelindaba

    The Treaty on the African Nuclear-Weapon-Free-Zone was opened for signature in Cairo in April 1996. The treaty prohibits the research, development, manufacturing, stockpiling, acquisition, testing, possession, control, and stationing of nuclear explosive devices on any member’s territory. The treaty also prohibits the dumping of radioactive waste originating from outside the continent within the region. In addition, the treaty requires parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities. The treaty also provides for the establishment of the African Commission on Nuclear Energy (AFCONE), which supervises treaty implementation and ensures compliance with its provisions.

  • Treaty of Rarotonga

    The Treaty on the South Pacific Nuclear-Weapon-Free Zone (SPNWFZ) prohibits the testing, manufacturing, acquiring, and stationing of nuclear explosive devices on any member’s territory. The treaty also prohibits the dumping of radioactive wastes into the sea. In addition, the treaty required all parties to apply International Atomic Energy Agency safeguards to all their peaceful nuclear activities.

  • Treaty of Tlatelolco

    This treaty, opened for signature in February 1967, created a nuclear-weapon-free zone in Latin America and the Caribbean. The Treaty of Tlatelolco was the first international agreement that aimed to exclude nuclear weapons from an inhabited region of the globe. The member states accept the application of International Atomic Energy Agency safeguards on all their nuclear activities. The treaty also establishes a regional organization, the Agency for the Prohibition of Nuclear Weapons in Latin America (OPANAL), to supervise treaty implementation and ensure compliance with its provisions.

  • Treaty on the Non-Proliferation of Nuclear Weapons (NPT)

    Signed in 1968, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is the most widely adhered-to international security agreement. The “three pillars” of the NPT are nuclear disarmament, nonproliferation, and peaceful uses of nuclear energy. Article VI of the NPT commits states possessing nuclear weapons to negotiate in good faith toward halting the arms race and the complete elimination of nuclear weapons. The Treaty stipulates that non-nuclear-weapon states will not seek to acquire nuclear weapons, and will accept International Atomic Energy Agency safeguards on their nuclear activities, while nuclear weapon states commit not to transfer nuclear weapons to other states. All states have a right to the peaceful use of nuclear energy, and should assist one another in its development. The NPT provides for conferences of member states to review treaty implementation at five-year intervals. Initially of a 25-year duration, the NPT was extended indefinitely in 1995.

  • Triad

    The concept of the triad integrates three forms of nuclear weapons deployment: intercontinental ballistic missiles (ICBMs); sea-launched ballistic missiles (SLBMs); and strategic bombers. The 2001 U.S. Nuclear Posture Review announced the development of a New Triad, which included the following “legs”: the first leg included non-nuclear and nuclear strike capabilities; the second leg included active and passive defense mechanisms, including ballistic missile defenses; and the third leg included responsive defense infrastructure, as part of an effort to better meet more amorphous and untraditional threats.

  • Triage

    A process for sorting injured or ill people into prioritized groups based on their need for and/or likely benefit from immediate medical treatment.

  • Trilateral Statement

    Signed by U.S. President Bill Clinton, Russian President Boris Yeltsin, and Ukrainian President Leonid Kravchuk in January 1994, the Trilateral Statement on the Non-Proliferation of Weapons of Mass Destruction and the Means of Their Delivery committed Ukraine to rid itself of nuclear weapons and to transfer 200 SS-19 and SS-24 warheads to Russia over a ten-month period. The Trilateral Statement also specified that Ukraine was to deactivate its SS-24s within the same ten-month period. The United States and Russia agreed to guarantee Ukraine’s borders and grant Ukraine security guarantees provided that Ukraine joined the NPT as a non-nuclear weapon state. Ukraine finished transferring its nuclear weapons to Russia in 1996 and acceded to the NPT as a non-nuclear weapon state in 1994. Also see the entry for Strategic Arms Reductions Talks.

  • Tularemia

    Tularemia is a disease caused by Francisella tularensis, a bacterium that is native to rabbits and aquatic mammals, but is also one of the most infectious pathogens to humans.  Tularemia can survive in harsh conditions, and just one organism can cause human infection.  Tularemia aerosols can incapacitate a patient within one or two days. Tularemia infection causes fever and skin lesions, and can eventually develop into pneumonia. The Soviet Union and Japan investigated F. tularensis for bioweapons purposes during World War II, as did the United States during the 1950s and 1960s.
  • Typhoid fever

    A disease spread through contaminated food, typhoid fever causes diarrhea and rash.  While typhoid fever is now only a public health concern in developing countries, typhoid fever outbreaks during wartime have occurred numerous times. Caused by the bacterium Salmonella typhi, Japan investigated and allegedly used typhoid-based biological weapons during sabotage operations in World War II.

  • Typhus

    Epidemic typhus has affected numerous military campaigns, including Napoleon’s invasion of Russia and the Eastern front during WWI. Typhus causes widespread vascular damage, and patients experience flu-like symptoms before the onset of delirium and neurological symptoms.  Because typhus is effectively treated by antibiotics, typhus is not considered a particularly significant BW threat.


  • Unauthorized launch

    The launch of a (nuclear) missile absent the authorization of the leadership legally endowed with such decision-making power. The term generally refers to an accidental or unintended launch that occurs because of faulty intelligence, systematic or mechanical failures, or the mistaken actions of military personnel.

  • United Nations Convention on the Law of the Sea

    The United Nations Convention on the Law of the Sea (UNCLOS) was opened for signature at Montego Bay, Jamaica, on 10 December 1982. It entered into force 12 year later on 16 November 1994. The Law of the Sea establishes a comprehensive legal framework to regulate all ocean space, its uses and resources. It contains, among other things, provisions relating to the territorial sea, the contiguous zone, the continental shelf, the exclusive economic zone, and the high seas. It also provides for the protection and preservation of the marine environment, for marine scientific research, and for the development and transfer of marine technology. For the purposes of nuclear weapon-free-zones, the most important provision of the UNCLOS is the right of innocent passage and freedom of the high seas.

  • United Nations Disarmament Commission (UNDC)

    The UNDC was established in 1952 as a deliberative body. The purpose of the UNDC is to examine and make recommendations on disarmament issues, and to follow-up and evaluate decisions made within special sessions.

  • United Nations General Assembly

    The UN General Assembly is the largest body of the United Nations. It includes all member states, but its resolutions are not legally binding. It is responsible for much of the work of the United Nations, including controlling finances, passing resolutions, and electing non-permanent members of the Security Council. It has two subsidiary bodies dealing particularly with security and disarmament: the UN General Assembly Committee on Disarmament and International Security (First Committee); and the UN Disarmament Commission.

  • United Nations Monitoring, Verification and Inspection Commission (UNMOVIC)

    The successor to the United Nations Special Commission on Iraq established by UN Security Council Resolution 1284 (1999), UNMOVIC was mandated to establish a reinforced, ongoing monitoring and verification system to check Iraq’s compliance with its obligations not to reacquire WMD. UNMOVIC was terminated in June 2007.  See entry for United Nations Special Commission on Iraq.

  • United Nations Security Council

    Under the United Nations Charter, the Security Council has primary responsibility for maintaining international peace and security. The Council consists of fifteen members, five of which—China, France, Russia, the United Kingdom, and the United States—are permanent members. The other ten members are elected by the General Assembly for two-year terms. The five permanent members possess veto powers.

  • United Nations Special Commission on Iraq (UNSCOM)

    An inspection and weapons destruction program established pursuant to paragraph 9(b)(l) of UN Security Council Resolution 687 (1991) following the 1990 to 1991 Gulf War. Section C of the resolution called for the elimination, under international supervision, of Iraq’s WMD and ballistic missiles with a range greater than 150 kilometers, together with related items and production facilities. It also called for measures to ensure that Iraq did not resume the acquisition and production of prohibited items. UNSCOM was set up to implement the non-nuclear provisions of the resolution, and to assist the International Atomic Energy Agency in the nuclear areas. It was replaced by UNMOVIC in 1999.

  • Unmanned Aerial Vehicle (UAV)

    Remotely piloted or self-piloted aircraft that can take on various intelligence or combat roles such as reconnaissance or targeted missiles strikes. The rapid proliferation of UAVs has raised concerns that they might serve as a delivery vehicle for a terrorist strike involving WMD.

  • UNSC Resolution 1540

    Resolution 1540 was passed by the UN Security Council in April 2004, calling on all states to refrain from supporting, by any means, non-state actors who attempt to acquire, use, or transfer chemical, biological or nuclear weapons or their delivery systems. The resolution also called for a Committee to report on the progress of the resolution, asking states to submit reports on steps taken towards conforming to the resolution. In April 2011, the Security Council voted to extend the mandate of the 1540 Committee for an additional 10 years.

  • UNSC Resolution 1887

    In September 2009, the UN Security Council committed to working toward the reduction of nuclear weapons and global nuclear dangers by adopting UNSCR 1887. In addition to calling for nuclear arms reductions, a strengthened NPT, greater support for the IAEA, and more robust export controls, the resolution also encouraged states to share best practices for improving nuclear safety and security standards, in order to reduce the risk of nuclear terrorism and to secure vulnerable nuclear materials within four years. The resolution also called on states to “minimize to the greatest extent that is technically and economically feasible the use of highly enriched uranium for civilian purposes, including by working to convert research reactors and radioisotope production processes to the use of low enriched uranium fuels and targets.” UNSCR 1887 also reaffirmed the need for full implementation of UNSCR 1540.

  • Uppsala Declaration on NWFZs

    The Uppsala Declaration on Nuclear-Weapon-Free Zones was adopted on 4 September 2000 at an international seminar attended by more than 50 experts, activists, and diplomats from six continents in Uppsala, Sweden. Participants discussed the feasibility of establishing new NWFZs across the world. In the declaration, participants adopted a program of future activities, including campaigns on both the regional and global levels for NWFZs, public education on the value of NWFZs with a view to creating new NWFZs, and strengthening existing NWFZs. See entry for Nuclear-Weapon-Free-Zone

  • Uranium

    Uranium is a metal with the atomic number 92. See entries for enriched uranium, low enriched uranium, and highly enriched uranium.

  • (U.S.) Schumer Amendment (1992)

    The (Charles E.) Schumer Amendment to the U.S. Energy Policy Act of 1992 required foreign reactors supplied with HEU fuel by the United States to commit to convert to LEU as quickly as possible, and prohibited U.S. HEU exports if foreign reactors did not undertake such obligations. The implementation of this Amendment in combination with LEU fuel development as part of the RERTR program, and a drop in the construction of new reactors, facilitated a rapid decline in U.S. HEU exports.

    See entries for Global Threat Reduction Initiative, radioisotopes, and the RERTR program.


  • VE

    A nerve agent, VE was originally discovered and first weaponized in the United Kingdom.  Like other nerve agents, VE causes uncontrollable nerve excitation and muscle excitation.  Within minutes, VE inhalation causes death by suffocation (respiratory paralysis).  Compared with other V-series nerve agents, VE is less toxic than VX but more toxic than VG, and is toxic enough to be suitable for weaponization.  VE is an oily, amber-colored, odorless liquid.

  • Vertical proliferation

    See entry for Proliferation.

  • VG

    A nerve agent, VG was originally discovered as a pesticide, and subsequently weaponized by the United Kingdom as one of the V-series nerve agents. Like other nerve agents, VG causes uncontrollable nerve excitation and muscle excitation.  Ultimately, VG inhalation causes death by suffocation (respiratory paralysis) within minutes.  While not as toxic as VX, VG is still highly toxic and suitable for weaponization.  VG is an oily, amber-colored, odorless liquid.

  • VM

    A nerve agent, VM was originally discovered and first weaponized in the United Kingdom.  Like other nerve agents, VM causes uncontrollable nerve excitation and muscle excitation.  Ultimately, VM victims suffer death by suffocation (respiratory paralysis).  While not as toxic as VX, VM is still highly toxic, and inhalation of VM can cause death within minutes. VM is an oily, amber-colored, odorless liquid.

  • Volatile

    In the context of chemical agents, the term volatile refers to substances that are readily vaporizable at normal temperatures and pressures.

  • Vomiting agent

    A vomiting agent is a chemical weapon that attacks the nose and throat, leading to nausea and severe emesis (vomiting).  Vomiting agents can be used to force an enemy to remove protective equipment such as gas masks. Examples include adamsite and DA.

  • VX

    The most toxic of the V-series nerve agents, VX was developed after the discovery of VE in the United Kingdom.  Like other nerve agents, VX causes uncontrollable nerve excitation and muscle excitation.  Ultimately, VX victims suffer death by suffocation.  VX is an oily, amber-colored, odorless liquid.


  • Warsaw Pact

    Created in 1955 by the Soviet Union and its six Central European satellites, this military and political security alliance was the counterpart of NATO. It was formally dissolved on 1 April 1991.

  • Wassenaar Arrangement (WA)

    Representatives of 33 states met in Vienna, Austria in July 1996, and established this arrangement intended to contribute to regional and international security by promoting transparency and greater responsibility with regard to transfers of conventional arms and dual-use goods and technologies. This organization was the successor to the Coordinating Committee for Multilateral Export Controls (COCOM). See entry for COCOM.

  • Weapons-grade material

    Refers to the nuclear materials that are most suitable for the manufacture of nuclear weapons, e.g., uranium (U) enriched to 90 percent U-235 or plutonium (Pu) that is primarily composed of Pu-239 and contains less than 7% Pu-240. Crude nuclear weapons (i.e., improvised nuclear devices), could be fabricated from lower-grade materials.

  • WMD Commission (Blix Commission)

    The WMD Commission was an independent commission chaired by former IAEA Director General and Executive Chairman of UNMOVIC, Hans Blix. Funded by the Swedish government, the Commission’s June 2006 report attributed the stagnation in global arms control and disarmament forums to a lack of commitment to disarmament by the nuclear weapon states.

  • WMD (weapons of mass destruction)

    Typically refers to nuclear, biological, or chemical weapons, though there is some debate as to whether chemical weapons qualify as weapons of “mass destruction.”


  • Yellow fever virus

    The virus that causes Yellow fever, a viral hemorrhagic fever.  Yellow fever is naturally transmitted by mosquitoes, and remains common in many tropical and semi-tropical areas, particularly in Africa.  Yellow fever patients experience two disease phases.  The first brings flu-like symptoms while the second phase, or “toxic phase,” brings severe pain, vomiting, kidney failure, and bleeding from the mouth, eyes, and stomach.  While only 15 to 25 percent of patients will develop the toxic phase, half of those who do die.  Very little open literature about possible weaponization of Yellow fever virus exists.

  • Yield

    The total amount of energy released by a nuclear explosion, generally measured in equivalent tons of trinitrotoluene (TNT). A kiloton is equivalent to 1,000 tons of TNT; a megaton is equivalent to one million tons of TNT.


  • Zangger Committee (ZC)

    A group of 35 nuclear exporting states established in 1971 under the chairmanship of Claude Zangger of Switzerland. The purpose of the committee is to maintain a “trigger list” of: (1) source or special fissionable materials, and (2) equipment or materials especially designed or prepared for the processing, use, or production of special fissionable materials. Additionally, the committee has identified certain dual-use technologies as requiring safeguarding when they are supplied to non-nuclear weapon states. These include explosives, centrifuge components, and special materials. The Zangger Committee is an informal arrangement, and its decisions are not legally binding upon its members.

  • Zone of Peace, Freedom and Neutrality (ZOPFAN)

    In November 1971, foreign ministers from ASEAN member states met and adopted the “ZOPFAN vision” in the Kuala Lumpur Declaration to establish the Zone of Peace, Freedom and Neutrality in Southeast Asia. The declaration states that ASEAN nations “are determined to exert initially necessary efforts to secure the recognition of, and respect for, Southeast Asia as a zone of peace, freedom and neutrality, free from any form or manner of interference by outside Powers.”