Treaties and Instruments Related to Arms Control, Disarmament, and Non-Proliferation of Nuclear Weapons

International Treaties Related to Nuclear Weapons Disarmament and Non-Proliferation

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), opened for signature on the 1st of July 1968, is an agreement which seeks to prevent nuclear proliferation, promote nuclear disarmament, and guide the peaceful use of nuclear energy. The treaty entered into force on the 5th of March 1970, and has 191 State parties.

The NPT is the cornerstone of global non-proliferation efforts which foster the peaceful use of nuclear energy and the furtherance of nuclear disarmament. Under the NPT, nuclear weapons states (NWSs) have committed, inter alia, not to consign nuclear weapons, nor be party in any manner to the manufacture or acquisition of nuclear weapons by non-nuclear-weapons states (NNWSs). NWSs are states that have both manufactured and exploded a nuclear weapon or other nuclear explosive devices, before 1 January 1967. Similar to the NPT other region specific nuclear weapons treaties require participating states to conclude a comprehensive safeguards agreement with the International Atomic Energy Agency (IAEA).

The Treaty on the Prohibition of Nuclear Weapons (TPNW), opened for signature on the 20th of September, 2017, is the first legally binding international agreement to comprehensively prohibit any nuclear weapon activities, with the ultimate goal being their total elimination. Under this treaty, state parties are also prohibited from stockpiling, stationing or using nuclear weapons as a threat. The TPNW makes provisions for assistance to individuals affected by the use or testing of nuclear weapons. In regions affected by contamination due to testing or use of nuclear weapons, environmental remediation measures are required from the state party with the jurisdiction in the region. The TPNW entered into force on the 22nd of January 2021 and has 73 State parties. An additional 25 parties have signed but not yet ratified their commitment. Opposition to the annual UN General Assembly resolution on the TPNW comes from NWSs.

The Partial Test Ban Treaty (PTBT), formally known as the Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, opened for signature on 5th of August 1963. Only nuclear tests conducted underground were exempted from prohibition under this treaty. The PTBT entered into force on the 10th of October 1963 and has 126 state parties.

The Comprehensive Nuclear-Test-Ban Treaty (CTBT), opened for signature on the 10th of September 1996, prohibits nuclear weapons test explosions as well as any other nuclear explosions, for both civilian and military purposes, in any environment. The CTBT has 178 state parties, but has not yet entered into force given that 9 required states have yet to ratify it. Commensurate with the entrance into force of the CTBT would be a comprehensive verification scheme. Typical measurements used to verify a nuclear test include:

• shockwaves from nuclear explosions can be detected using seismic instruments as they travel through the ground
• sound waves generated by a nuclear detonation in or near a body of water can be detected at Hydroacoustic stations
• infrasonic waves that propagate through the atmosphere subsequent to a nuclear detonation can be detected on sensors that register frequencies inaudible to the human ear
• radioactive particles and gases produced by a nuclear detonation and released into the atmosphere can be monitored at various radionuclide stations
• satellite imagery can be used to capture the craters and debris fields left behind after a nuclear detonation, as well as to monitor the activity around known nuclear testing and storage facilities

In order to verify nuclear testing on a global scale, an international observational network is required. The International Monitoring System (IMS) is one such network, specifically established to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty when it enters into force. The IMS is comprised of 321 monitoring stations across the globe, with an additional 16 radionuclide laboratories. Data from this network is processed at a 24-hour monitoring facility, the International Data Centre (IDC). The IDC, with headquarters in Vienna, screens the data for possible nuclear testing events and presents this information to member states. Upon inspection of information presented by the IMS, a member state that perceives a possible breach of a treaty may proceed further to request an on-site inspection. An international team of inspectors can then be dispatched to investigate the suspected breach at the site.

The Antarctic Treaty, opened for signature on the 1st of December 1959, protects the peaceful status of the Antarctic Continent. The testing of nuclear weapons and the disposal of radioactive waste material is prohibited on the Antarctic content. This treaty has 55 state parties and entered into force on the 23rd of June 1961.

The Outer Space Treaty, opened for signature on the 27th of January 1967, prohibits the stationing of weapons of mass destruction (WMDs) in space, or in orbit around any celestial body. Importantly, this treaty recognizes that no one particular nation may claim sovereignty over outer space or any celestial body. The Outer Space Treaty, more formally known as the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, has 115 state parties and entered into force on the 10th of October 1967.

The Seabed Arms Control Treaty, formally known as the Treaty on the Prohibition of the Emplacement of Nuclear Weapons and Other Weapons of Mass Destruction on the Sea-Bed and the Ocean Floor and in the Subsoil Thereof, was opened for signature on the 11th of February 1971. The treaty prohibits the stationing of WMDs on the ocean floor beyond a 12-mile (22.2 kilometer) coastal zone, has 94 state parties, and entered into force on the 18th of May 1972. It allows state parties to observe other stateparties’ seabed activities beyond the coastal zone in order to verify compliance with the treaty.

The Fissile Material Cut-off Treaty (FMCT), the terms of which are yet to be negotiated, is proposed to be a prohibition on further production of fissile material which would be used in nuclear weapons or other explosive devices.

Region Specific Nuclear Weapon Free Zone Treaties

The Treaty of Tlatelolco, otherwise known as the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean, opened for signature on the 14th of February 1967 and prohibits the testing, use, manufacture, production or acquisition by any means whatsoever of any nuclear weapons as well as the receipt, storage, installation, deployment and any form of nuclear weapons possession. The Treaty of Tlatelolco has 33 state parties and entered into force on the 22nd of April 1968.

The Treaty of Rarotonga, opened for signature on the 6th of August 1985 and otherwise known as the South Pacific Nuclear Free Zone Treaty, prohibits the use, testing, and possession of nuclear weapons within the borders of the South Pacific. This treaty has 13 state parties and entered into force on the 11th of December 1986.

The Treaty of Bangkok, otherwise known as the Treaty on the Southeast Asia Nuclear Weapon-Free Zone Treaty, opened for signature on the 15th of December 1995 and is a commitment to keep the Southeast Asian region free from nuclear and other weapons of mass destruction. This treaty entered into force on the 28th of March 1997 and has 10 state parties.

The Treaty of Pelindaba, otherwise known as the African Nuclear-Weapon-Free Zone Treaty, opened for signature on the 11th of April 1996 and prohibits the research, development, manufacture, stockpiling, acquisition, testing, possession, control, or stationing of nuclear explosive devices. The Treaty of Pelindaba has 43 state parties and entered into force on the 15th of July 2009.

The Treaty of Semipalatinsk, otherwise known as the Treaty on a Nuclear-Weapon-Free Zone in Central Asia, opened for signature on the 8th of September 2006 and is a commitment to refrain from the manufacture, acquisition, testing, or possession of nuclear weapons. The treaty of Semipalatinsk has 5 state parties and entered into force on the 21st of March 2009.

Bilateral Agreements between the United States and the Soviet Union surrounding arms control

The Anti-Ballistic Missile (ABM) Treaty, signed on the 26th of May 1972, placed limitations on the number of anti-ballistic missile systems used in defense against ballistic missile-delivered nuclear weapons. Each party was be limited to 100 anti-ballistic missiles. The ABM treaty was intended to reduce pressure to build more nuclear weapons as a means to achieve deterrence. This bilateral agreement between the United States and the Soviet Union entered into force on the 3rd of October 1972. The United States withdrew from this agreement on the 13th of June 2002.

The Threshold Test Ban Treaty (TTBT) signed on the 3rd of July 1974, prohibits nuclear tests with devices having a yield exceeding 150 kilotons. This treaty addresses the exception in the PTBT for nuclear underground tests and is thus formally known as the Treaty on the Limitation of Underground Nuclear Weapon Tests. The TTBT only entered into force on the 11th of December 1990 and was a bilateral agreement between the United States and the Soviet Union.

The Peaceful Nuclear Explosions (PNE) Treaty, signed on the 28th of May 1976, was a bilateral agreement between the United States and the Soviet Union prohibiting peaceful nuclear explosions which were not addressed within the scope of the TTBT. Single explosions with yields exceeding 150 kilotons and group explosions having an aggregate yield of over 1500 kilotons (none of which may be more than 150 kilotons each) are the subject of the PNE treaty, which entered into force on the 11th of December 1990. Additionally, the PNE treaty addresses explosions at locations not designated as test sites under the TTBT.

The New Strategic Arms Reductions Treaty (New START), signed on the 8th of April 2010, limits the number of deployed strategic nuclear warheads to 1550, deployed missiles and bombers to 700, and deployed and non-deployed launchers (missile tubes and bombers) to 800. The New START treaty entered into force on the 5th of February 2011 and is a bilateral agreement between the United States and Russia.

Current Global Posture on Nuclear Disarmament and Typical Treaty Verification Techniques

According to the Federation of American Scientists (FAS), there was an estimated global stockpile of 70,300 nuclear weapons during the Cold War. Figures 1 and 2 serve to elucidate the current global posture on nuclear weapons, providing estimates of the current stockpile per armed state (estimates courtesy of the Arms Control Association).

South Africa retired its nuclear weapons program in 1991 and is the only state to have voluntarily relinquished nuclear weapons (South Africa reported having had six weapons at the time). The nuclear weapons of Belarus, Kazakhstan, and Ukraine were transferred to Russia within the context of the Lisbon Protocol.

Nuclear weapons can fall into two categories: strategic nuclear weapons, which are designed to engage remote regions (ranges greater than 5500 km), and non-strategic nuclear weapons. Non-strategic nuclear weapons include classifications for tactical and operational nuclear weapons. The definition of each classification will vary slightly by country and with the capability to employ nuclear weapons by land, sea, or air, but generally, non-strategic weapons are those with ranges less than 5500 km. The bilateral New START treaty between the United States and Russia entered into force on the 5th of February 2011 and limits the number of deployed strategic weapons.

The IAEA has been designated as the international safeguards inspectorate under Article III of the NPT. The IAEA Safeguards provide a mechanism of deterrence against the spread of nuclear weapons. The early detection of the misuse of nuclear material (or nuclear technology) grants credible assurance that nuclear material (or nuclear technology) is not being diverted from peaceful purposes. Part of the IAEA safeguarding process is a mechanism known as nuclear material accountancy, wherein the quantities of nuclear materials present in a nuclear facility, along with the change of these quantities over time, is accounted for. The IAEA considers all “source or special fissionable material”, which are those significant to the manufacture of nuclear weapons. To ensure the containment of such materials, the IAEA has installed more than 23 000 seals at nuclear facilities. Some examples of special fissionable materials include plutonium-239, uranium-233, and uranium enriched in uranium-235 (as well as any material containing a combination of these).

Also included in the safeguarding process is the evaluation of a state’s nuclear activities by means of on-site inspections. Visits to a nuclear facility, by the IAEA, allow for the verification of design information as well as environmental sampling. Valuable information on a state’s nuclear activities may also be collected remotely using satellite imagery. The IAEA surveillance system (1400 surveillance cameras, 400 radiation and other sensors) captures in excess of a million pieces of encrypted safeguards data.

Instruments Supporting Disarmament and Non-Proliferation of Nuclear Weapons

Zangger Committee

After the Nuclear Non-Proliferation Treaty entered into force on the 5th of March 1970, the Zangger Committee was formed. The Zangger Committee, also known as the Nuclear Exporters Committee, has 39 members including all the nuclear weapon states (those specific to the NPT). The objective of the committee meetings was to gain greater collective clarity on Article III, paragraph 2 of the Nuclear Non-Proliferation Treaty. The Zangger Committee maintains a list of nuclear strategic goods (and equipment) which are subject to export controls. This “Trigger List” is intended to assist signatories of the Nuclear Non-Proliferation Treaty in ensuring that recipients of strategic goods and equipment incorporate the obligatory safeguards.

Nuclear Suppliers Group

The Nuclear Suppliers Group (NSG), founded in response to India’s first nuclear weapon test of May 1974, is a group of countries that seeks to contribute to the non-proliferation of nuclear weapons through the implementation of two sets of guidelines for nuclear exports and nuclear-related exports. The aim of the NSG Guidelines is to ensure that nuclear trade for peaceful purposes does not contribute to the proliferation of nuclear weapons or other nuclear explosive devices, and that international trade and cooperation in the nuclear field is not hindered unjustly in the process.

Convention on the Physical Protection of Nuclear Material and Nuclear Facilities

The Convention on the Physical Protection of Nuclear Material and Nuclear Facilities, signed on 26 October 1979, seeks to ensure the effective physical protection during the use, storage or transport of nuclear material used for peaceful purposes, as well as preventing and fighting crime associated with this material and related facilities. Each party to the convention must draw up and implement measures to guarantee effective protection against the theft or disappearance of nuclear material which it is responsible and to prevent the sabotage of nuclear facilities on its territory.

Missile Technology Control Regime

Formed in April 1987, the voluntary Missile Technology Control Regime (MTCR) is a multilateral export control regime which aims to curb the spread of unmanned delivery systems that could be used for chemical, biological, or nuclear attacks. The 35 members are encouraged to restrict their exports of technologies capable of carrying a 500-kilogram payload at least 300 kilometers, or of delivering any type of weapon of mass destruction. Additionally, members are responsible for the establishment of national export control policies for ballistic missiles, cruise missiles, unmanned aerial vehicles, space launch vehicles, drones, remotely piloted vehicles, sounding rockets, and underlying components and technologies that appear on the regime’s Material and Technology Annex.

Ballistic Missile Launch Notification Agreement

Signed at the Moscow summit on the 31st of May 1988, the agreement asserts that any launch of an intercontinental ballistic missile (ICBM) or a submarine-launched ballistic missile (SLBM) should be declared by Nuclear Risk Reduction Centers, no less than 24 hours in advance of the planned launch date. The launch location, as well as the area of impact, should be declared in the notification. This agreement specifically addresses concerns surrounding the risk of the outbreak of nuclear war as a consequence of misinterpretation or miscalculation.

Lisbon Protocol

The Lisbon Protocol to the 1991 Strategic Arms Reduction Treaty, was signed on May 23rd, 1992, by representatives of Russia, Belarus, Ukraine, and Kazakhstan. Article V of the protocol stipulates signatories, as non-nuclear weapon states, shall adhere expeditiously to the NPT. It should be emphasized that article V is not applicable to Russia.

The Wassenaar Arrangement

On the 12th of July 1996, the Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies was established to contribute to regional and international security and stability.

Through the promotion of transparency and responsible conduct in the export of conventional arms and dual-use goods (material, software, and technology), it aims to prevent the accumulation of destabilizing weapons. The prevention of the acquisition of these goods by terrorists is also an objective under this agreement. Member States are encouraged to prevent exports of these goods (through their national policies) that may augment the development of military capabilities by those seeking to thwart the objectives of the agreement.

Hague Code of Conduct Against Ballistic Missile Proliferation

On the 25th of November 2002, the Hague Code of Conduct Against Ballistic Missile Proliferation (formerly known as the International Code of Conduct Against Ballistic Missile Proliferation), was established to regulate access to ballistic missiles which can potentially deliver weapons of mass destruction. It is the only normative instrument to verify the spread of ballistic missiles. Active participation requires the exchange of information regarding ballistic missile and space launch vehicle programs, carried out annually between members. Under the Code, provisions should be made to deliver advanced notice of any launches of ballistic missiles or space launch vehicles. The Hague Code of Conduct has 145 member states (including MTCR members). Brazil has yet to adopt membership after articulating reservations surrounding possible limitations of its space program.

United Nations Security Council Resolution 1540 and 2663

Resolution 1540 of the United Nations Security Council, signed on the 28th of April 2004, stipulates that all States shall refrain from providing any form of support to non-State actors that attempt to develop, acquire, manufacture, possess, transport, transfer, or use nuclear, chemical or biological weapons and their means of delivery, in particular for terrorist purposes. All States are required to adopt and enforce appropriate laws and preventative measures to this end. Resolution 2663, adopted on the 30th of November 2022, extends the mandate of the subsidiary 1540 Committee for a period of ten years until the 30th of November 2032.

The Joint Comprehensive Plan of Action

On the 14th of July 2015, the Joint Comprehensive Plan of Action (JCPOA) agreement was reached between Iran, the P5+1 (five permanent members of the United Nations Security council + Germany) and the European Union. This agreement, also known as the Iran Nuclear Deal, places limitations over the Iranian nuclear program in return for sanctions relief and other provisions. Specifically, Iran agreed to open its nuclear facilities to increasingly extensive international inspections and to reduce its nuclear program appreciably. The JCPOA currently has seven signatories: China, France, Germany, Iran, Russia, United Kingdom and the European Union. The United States of America withdrew on the 8th of May 2018.