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Anti-ballistic missile (ABM) system - Generally comprised of radars, sensors, launchers, and interceptors, this weapon system is intended to intercept and destroy long-range ballistic missiles and their warheads in flight. The term is often used interchangeably with ballistic missile defense (BMD). See also, "ballistic missile defense," "Strategic Defense Initiative," and "theater missile defense."


Anti-Ballistic Missile (ABM) Treaty - Formally known as "Treaty on the Limitation of Anti-Ballistic Missile Systems," the ABM Treaty was signed by the United States and the Soviet Union on May 26, 1972, that restricted each state to two ABM deployment areas (each with up 100 ABM launchers and interceptors) so that either party would have some of its territory exposed to a retaliatory nuclear strike from the other, thereby helping to maintain a nuclear deterrence relationship. A protocol signed in July 1974 further limited ABM deployment areas to a single location for either party. On December 13, 2001, the United States announced its intent to withdraw from the ABM Treaty, declaring that US-Russia security relations no longer rested on nuclear deterrence and that pursuit of missile defenses against "rogue states" required abandoning the Treaty. US withdrawal from the ABM Treaty officially took effect on June 13, 2002.


Australia Group - A voluntary association of 38 states (all signatories to the Chemical Weapons Convention and the Biological Weapons Convention) established in 1985 that coordinates export licensing of materials and equipment related to the development of chemical and biological weapons (biological weapons were added in 1990). Australia Group's "common control list" requires licensing for export of certain chemical precursors, dual-use chemical and biological equipment, plant and animal pathogens, and biological agents. The government of Australia, which initially proposed a meeting of interested parties in April 1985, serves as the informal chair of the association. Australia Group official website.



Ballistic missile - Missiles propelled upwards on a trajectory towards a ground target. Ballistic missiles lack guidance systems (except for the initial, upward, boost phase) and are essentially rocketed into the sky (at times beyond the atmosphere) before free falling on the target area in a steep arc.


Ballistic missile defense (BMD) - A system designed to identify, target, intercept, and destroy incoming ballistic missiles in flight.


Biological warfare/weapons (BW) - Use of living organisms, toxic biological products, and plant growth regulators to produce death, disease, or incapacitation in humans, animals, or plants.


Biological and Toxins Weapons Convention (BTWC) - Also known as the Biological Weapons Convention (BWC), the BTWC is a treaty banning biological and toxin weapons opened for signature on April 10, 1972, and ratified by the United States on January 22, 1975. The more than 100 parties to the convention undertake not to develop, produce, stockpile, or acquire biological agents or toxins "of types and quantities that have no justification for prophylactic, protective, and other peaceful purposes," as well as related weapons and means of delivery. There are no verification or enforcement provisions in the treaty itself, though states may bring up any cases of violation at the UN Security Council. University of Bradford website on the BWTC.


Biological Threat Reduction Program (BTRP) - Formerly known as the Biological Weapons Proliferation Prevention (BWPP) program, BTRP encompasses several Department of Defense programs that reduce the risk of biological weapons proliferation in the FSU while still allowing for legitimate, peaceful research using biological materials.


Biological Weapons Convention (BWC) - See Biological and Toxins Weapons Convention (BTWC) above.


Breeder reactor - A nuclear reactor that produces more fissile material than it consumes while generating power.



Centrifuge - A rapidly-spinning cylinder that uses the different masses of isotopes to slowly separate those isotopes in gaseous form; used to enrich uranium.


Chemical warfare/weapons (CW) - The use of non-living chemical substances and/or toxins to kill, incapacitate, harass, or control. Among the chemical agents developed for military use are chlorine, phosgene, mustard gas, the nerve agents GB (Sarin) and VX, and a riot control agent called CS. A chemical agent refers to the harmful chemical itself, whereas a weapon usually refers to the agent and its delivery systems.


Chemical Weapons Convention (CWC) - Opened for signature on January 13, 1993, the CWC is intended to eliminate chemical weapons around the world. Parties to the convention undertake not to develop, produce, acquire, stockpile, transfer, or use chemical weapons. Due to the dual-use nature of many chemical agents, the CWC has a great impact on civilian industries. As of November 19, 2004, 167 states have become parties to the convention. The Organisation for the Prohibition of Chemical Weapons (OPCW) was established in the Hague in 1997, the year the CWC entered into force. The OPCW is responsible for implementing the CWC through on-site inspections, information sharing, and provision of training and resources to enhance preparedness of parties against chemical attacks. OPCW official website.


Chemical Weapons Destruction (CWD) - CTR program to destroy chemical weapons in Russia.


Coolant - A substance circulated through a nuclear reactor to remove or transfer heat. Coolants may be water, heavy water, carbon dioxide, helium, sodium, or sodium-potassium alloy. In power reactors, steam from the heated coolant can be used to rotate turbines in order to generage energy.


Cooperative Nonproliferation (CNP) - The term used to describe US government programs aimed at reducing the threat of the proliferation of weapons of mass destruction, their delivery systems, and WMD-related expertise by working cooperatively with other countries. CNP projects are carried out mainly by the Departments of Defense, Energy, and State.


Cooperative Threat Reduction (CTR) - A suite of programs begun by the Soviet Nuclear Threat Reduction Act of 1991 that attempt to secure or dismantle WMD, their delivery vehicles, and related infrastructure and materials through cooperative methods. CTR projects come under the jurisdiction of the Department of Defense and are aimed towards preventing WMD proliferation in Russia and the former Soviet Union.


Core - The central portion of a nuclear reactor containing the fuel elements.



Defense and Military (Def-Mil) Contacts - CTR programs aiming to strengthen partnerships between US defense agencies and their counterparts in the FSU.


Delivery vehicle - Weapon system that carries one or more warheads to the target area (e.g., cruise or ballistic missiles, bombers, etc.).


Dual-use - Capable of having both civilian, industrial and military applications. For example, certain biological samples could be used to produce pharmaceutical products like vaccines or to construct biological weapons.



Fissile materials - Material that can undergo nuclear fission (i.e. release large amounts of energy by splitting atoms) when struck with "slow" or "low-energy" neutrons. Fissile materials are particularly useful for fueling nuclear reactors or creating nuclear weapons. Examples of fissile materials include uranium (U-233 and U-235) and plutonium (Pu-239).


Fission - The process of splitting atomic nuclei by bombarding the nuclei with neutrons. The split nuclei result in the release of enormous amounts of energy and more neutrons capable of splitting other atoms.


Former Soviet Union (FSU) - Independent states that used to make up the Union of Soviet Socialist Republics (USSR), including Russia, Estonia, Latvia, Lithuania, Belarus, Moldova, Ukraine, Georgia, Armenia, Azerbaijan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan.


Fuel rod - Tube, up to four or five meters (or about 15 feet) long and usually made of zircalloy, containing the fuel for a nuclear reactor.



Heavy water (deuterium oxide) - Water found in nature that is composed of deuterium (or "heavy hydrogen") and oxygen (D2O or 2H2O instead of the usual H2O). It is often used as a moderator in nuclear reactors as heavy water slows down neutrons and does not absorb them, unlike ordinary water. This helps sustain a chain reaction within uranium-fueled reactors. Heavy water reactors are nuclear reactors that use heavy water as a moderator (and perhaps coolant).


Highly-enriched uranium (HEU) - Uranium is normally found in nature with 0.7% of the total composed of U-235, an isotope of uranium that is particularly conducive to nuclear fission. HEU is uranium with an artificially increased U-235 concentration of 20% or more, which can then be used to assemble very crude nuclear weapons. "Weapons-grade" uranium, used in the creation of most nuclear weapons, often refers to HEU with 85-90% or more U-235. HEU with lesser concentrations of U-235 is also used for fueling research reactors and nuclear submarines.



Initiatives for Proliferation Prevention (IPP) - Department of Energy program that creates economic opportunities in the commercial sectors for former Soviet WMD scientists through private-public partnerships. Stably-employed former WMD scientists are less likely to transfer WMD expertise to states and terrorists desiring nuclear weapons.


Intercontinental ballistic missile (ICBM) - Long-range, land-based missile with a maximum target range exceeding 5,500 km (roughly 3,400 miles or the distance between the US and Russia). They often carry nuclear warheads, having played a critical role in the US-Soviet standoff during the Cold War. See also, "ballistic missile."


International Atomic Energy Agency (IAEA) - An independent organization, founded in 1957 within the United Nations and headquartered in Vienna, that promotes nuclear non-proliferation through safeguards and verifications and that advances peaceful and safe uses of nuclear energy through scientific research and technical cooperation. The organization also administers the safeguards in non-nuclear-weapons states as required of signatories to Non-Proliferation Treaty. The IAEA is composed of the General Conference of all 138 member states, which reviews budgets and proposals brought to it by the 35-member Board of Governors. The work of the IAEA is supported by its own Secretariat with a staff of 2,200 personnel from over 90 countries. IAEA official website.


International Science and Technology Center (ISTC) - Established in November 1992 by international agreement amongst Russia, the United States, the European Union, and Japan, the ISTC has the primary objective of connecting former Soviet WMD scientists with market demands for expertise in the fields of biology, chemistry, and nuclear science. By giving former weapons scientists a stable job in one of its science projects, ISTC and contributing governments and organizations prevent WMD "know-how" from falling into the wrong hands. At the same time, ISTC helps countries of the FSU transition to market economies and transform a militarized scientific community into a peaceful one that tackles civilian issues, such as public and agricultural health, renewable energy, and counter-terrorism. The ISTC has headquarters in Moscow and maintains branch offices and projects in Russia, Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, and Tajikistan. ISTC official website.


Isotopes - Chemically identical atoms of the same element with different numbers of neutrons in their nuclei and thus different atomic masses (e.g., U-238 and U-235).



Light water - Ordinary water (H2O) to be distinguished from heavy water (D2O or 2H2O) when used as a moderator or coolant in nuclear reactors.


Low-enriched uranium (LEU) - Uranium is normally found in nature with 0.7% of the total composed of U-235, an isotope of uranium that is particularly conducive to nuclear fission. LEU is uranium with an increased concentration of U-235 but less than 20% of total weight made up of that isotope. LEU of 2-5% U-235 is used in commercial reactors, such as those producing power for heat and electricity. The goal of several CNP programs dealing with nuclear weapons and materials is to reduce the level of U-235 in weapons-grade uranium, converting the HEU into LEU, which can then be used for commercial purposes. Also known as "lightly-enriched uranium."



Material protection, control, and accounting (MPC&A) - A comprehensive system to 1) physically protect the nuclear materials themselves, 2) control access to and movement of nuclear materials, and 3) keep track of nuclear materials (including quantity and location) through databases and inventories.


Missile Technology Control Regime (MTCR) - An informal association of 34 states founded in 1987 that facilitates information sharing and coordination on export licensing of technologies used in manufacturing missiles and rockets, especially those intended to carry WMD. MTCR produced the MTCR Guidelines, which sets out common export policy guidelines, and the Equipment, Software, and Technology Annex, which lists items to be controlled. MTCR official website.


Mixed oxide (MOX) fuel - Combination of plutonium (Pu-239) from spent fuel rods and natural, low enriched, or depleted uranium left over from enrichment plants. MOX fuel is one way to recycle nuclear fuel for commercial energy reactors, but the process creating MOX fuel can also be used to convert weapons-grade plutonium into a form that simultaneously cannot be employed in weapons development yet can produce energy for heating and electricity.


Moderator - Part of the nuclear reactor that slows down neutrons enough to hit and split uranium (U-235). Materials used as a moderator include ordinary/light water, heavy water, and graphite.



Non-Proliferation Treaty (NPT) - Signed in 1968 and entering into force in 1970, the NPT's signatories (187 to date) pledge to cap the number of states possessing nuclear weapons to the five permanent members of the UN Security Council (United States, United Kingdom, France, Russian Federation, and People's Republic of China). All other member states vowed not to develop nuclear weapons and, under Article III of the NPT, to cooperate with the IAEA's safeguards mechanisms to verify their compliance with the terms of the treaty. The five nuclear-weapons states, in turn, promised not only to prevent nuclear proliferation but also to assist non-nuclear-weapons states, especially developing countries, in accessing peaceful nuclear technologies. The NPT also encourages all nuclear-weapons states to disarm, promotes the creation of nuclear-weapons-free zones, and calls for a review conference every five years. UN website on NPT. US Department of State website on NPT.


Nuclear Cities Initiative (NCI) - Expire CNP program run by the US Department of Energy in conjunction with Russian Federal Atomic Energy Agency that aimed to downsize the Russian nuclear weapons complex by converting facilities in Russia's ten closed nuclear cities into civilian production plants.


Nuclear Weapons Storage Security (NWSS) - CTR program aimed at improving safety and security at nuclear weapons storage facilities in Russia. 


Nuclear Weapons Transportation Security (NWTS) - CTR program to enhance security of nuclear weapons while being transported to dismantlement sites.



Organisation for the Prohibition of Chemical Weapons (OPCW) - International body established in 1997 and responsible for implementing the Chemical Weapons Convention. See Chemical Weapons Convention (CWC) above. OPCW's official website.



Plutonium - Rarely found in nature, plutonium is a heavy element usually manufactured through the irradiation of uranium (U-238) in a nuclear reactor. Pu-239 (a particular isotope of plutonium) can be used in fueling reactors or in the creation of nuclear weapons. Weapons-grade plutonium refers to plutonium with a high concentration (90% or more) of Pu-239.


Proliferation Prevention Initiative (PPI) - CTR program to enhance border security in the FSU to prevent WMD proliferation.



Safeguards - The system of control and handling of nuclear materials that subjects them to domestic and international (IAEA) inspections as agreed upon in treaties and agreements and in domestic legislation.


Science and Technology Center in Ukraine (STCU) - Established in October 1993 by international agreement amongst Ukraine, Canada, Sweden (later replaced by the EU), and the United States, the STCU develops and funds projects for former Soviet WMD scientists enabling them to apply their expertise in peaceful pursuits. With headquarters in Kyiv, Ukraine, STCU maintains offices and projects in Ukraine, Azerbaijan, Georgia, Moldova, and Uzbekistan. STCU official website.


Science and Technology Center - One of two institutions (Moscow, Russia and Kyiv, Ukraine, respectively) that support efforts to provide peaceful, commercial opportunities for former Soviet weapons scientists in order to prevent the proliferation of WMD expertise.


SSBN - US Navy classification symbol for nuclear-powered submarine armed with ballistic missiles, often deployed on strategic, nuclear deterrence missions; SS stands for ship submersible, B denotes the ability to carry ballistic missiles, while N shows the ship is nuclear powered.


Strategic Defense Initiative (SDI) - Also known as "Star Wars," SDI is a defense research and development program started in 1983 to devise a system of radars and space-based weapons to destroy hostile ballistic missiles in flight. Controversial throughout its lifespan, the program was eventually terminated in the 1990s. See also, "anti-ballistic missile system," "ballistic missile defense" and "theater missile defense."


Strategic Offensive Arms Elimination (SOAE) - CTR program focusing on WMD-delivery vehicles in Russia.


Submarine-launched ballistic missile (SLBM) - Ballistic missile capable of being launched from a submarine.



Theater missile defense (TMD) - Defensive measures intended to protect forces operating in a given region, or theater, from short- and medium-range missile attacks. See also, "anti-ballistic missile system" and "ballistic missile defense."



Weapons of mass destruction (WMD) - A category of weapons including nuclear, chemical, and biological arms. At times, WMD can also include radiological weapons, or "dirty bombs," that disperse radioactive material along with the detonation of a conventional explosive device. Variations of the term WMD include: NBC (nuclear, biological, chemical), WMD (weapons of mass disruption), and CBRN (chemical, biological, radiological, nuclear). See also Bugs, Bombs, and Deadly Gases: The WMD Reference Center.


Weapons-grade material - Uranium that consists of more than 90% of the isotope U-235, or plutonium that is 90% or more Pu-239. Note that such high concentrations of either isotope are not necessary for the construction of crude or radiological weapons. See also, "highly-enriched uranium" and "plutonium."



Yield - The amount of energy released by a nuclear explosion, generally measured in equivalent tons of TNT. A kiloton is equal to 1,000 tons of TNT; a megaton is equal to one million tons of TNT.




Zangger Committee - An informal association of 35 states (including all permanent members of the UN Security Council) that grew out of a series of meetings in Vienna from 1971 to 1974 chaired by Professor Claude Zangger of Switzerland. The Committee drew up (and continues to update) a list of what materials and equipment ought to cause concern for the international community if exported to non-nuclear states (i.e. states that do not have nuclear weapons). Transfer of materials on this "Trigger List" recommends, under the Non-Proliferation Treaty, IAEA safeguards to ensure that they are not diverted to arms development. However, decisions by the Zangger Committee are not legally binding. Zangger Committee official website.


For more detailed background information on many of these issues, click here to visit the Stimson Center's WMD Reference Center.