The Comprehensive Nuclear-Test-Ban Treaty (CTBT) is a
multilateral treaty
A multilateral treaty is a treaty to which two or more sovereign states are parties. Each party owes the same obligations to all other parties, except to the extent that they have stated reservations. Examples of multilateral treaties include th ...
to ban
nuclear weapons test explosions and any other
nuclear explosions
A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, th ...
, for both civilian and military purposes, in all environments. It was adopted by the
United Nations General Assembly
The United Nations General Assembly (UNGA or GA; french: link=no, Assemblée générale, AG) is one of the six principal organs of the United Nations (UN), serving as the main deliberative, policymaking, and representative organ of the UN. Cur ...
on 10 September 1996, but has not
entered into force, as eight specific nations have not ratified the treaty.
History
The movement for international control of
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
s began in 1945, with a call from Canada and the United Kingdom for a conference on the subject. In June 1946,
Bernard Baruch
Bernard Mannes Baruch (August 19, 1870 – June 20, 1965) was an American financier and statesman.
After amassing a fortune on the New York Stock Exchange, he impressed President Woodrow Wilson by managing the nation's economic mobilization in ...
, an emissary of President
Harry S. Truman, proposed the
Baruch Plan before the United Nations Atomic Energy Commission, which called for an international system of controls on the production of atomic energy. The plan, which would serve as the basis for U.S. nuclear policy into the 1950s, was rejected by the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
as a US ploy to cement its nuclear dominance.
Between the
Trinity nuclear test of 16 July 1945 and the signing of the
Partial Test Ban Treaty
The Partial Test Ban Treaty (PTBT) is the abbreviated name of the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, which prohibited all test detonations of nuclear weapons except for those conducted u ...
(PTBT) on 5 August 1963, 499 nuclear tests were conducted.
Much of the impetus for the PTBT, the precursor to the CTBT, was rising public concern surrounding the size and resulting
nuclear fallout
Nuclear fallout is the residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioa ...
from underwater and atmospheric nuclear tests, particularly tests of powerful
thermonuclear weapons (hydrogen bombs). The
Castle Bravo
Castle Bravo was the first in a series of high-yield thermonuclear weapon design tests conducted by the United States at Bikini Atoll, Marshall Islands, as part of ''Operation Castle''. Detonated on March 1, 1954, the device was the most powerful ...
test of 1 March 1954, in particular, attracted significant attention as the detonation resulted in fallout that spread over inhabited areas and sickened a group of Japanese fishermen.
Between 1945 and 1963, the US conducted 215 atmospheric tests, the Soviet Union conducted 219, the UK conducted 21, and
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...
conducted three.
In 1954, following the Castle Bravo test, Prime Minister
Jawaharlal Nehru
Pandit Jawaharlal Nehru (; ; ; 14 November 1889 – 27 May 1964) was an Indian anti-colonial nationalist, secular humanist, social democrat—
*
*
*
* and author who was a central figure in India during the middle of the 20t ...
of
India
India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...
issued the first appeal for a "standstill agreement" on testing, which was soon echoed by the British
Labour Party.
Negotiations on a comprehensive test ban, primarily involved the US, UK, and the Soviet Union, began in 1955 following a proposal by Soviet leader
Nikita Khrushchev
Nikita Sergeyevich Khrushchev (– 11 September 1971) was the First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and chairman of the country's Council of Ministers from 1958 to 1964. During his rule, Khrushchev ...
. Of primary concern throughout the negotiations, which would stretch with some interruptions to July 1963, was the system of verifying compliance with the test ban and detecting illicit tests. On the Western side, there were concerns that the Soviet Union would be able to circumvent any test ban and secretly leap ahead in the
nuclear arms race
The nuclear arms race was an arms race competition for supremacy in nuclear warfare between the United States, the Soviet Union, and their respective allies during the Cold War. During this same period, in addition to the American and Soviet n ...
. These fears were amplified following the US
''Rainier'' shot of 19 September 1957, which was the first contained underground test of a nuclear weapon. Though the US held a significant advantage in underground testing capabilities, there was worry that the Soviet Union would be able to covertly conduct underground tests during a test ban, as underground detonations were more challenging to detect than above-ground tests. On the Soviet side, conversely, the on-site compliance inspections demanded by the US and UK were seen as amounting to espionage. Disagreement over verification would lead to the Anglo-American and Soviet negotiators abandoning a comprehensive test ban (i.e., a ban on all tests, including those underground) in favor of a partial ban, which would be finalized on 25 July 1963. The PTBT, joined by 123 states following the original three parties, banned detonations for military and civilian purposes underwater, in the atmosphere, and outer space.
The PTBT had mixed results. On the one hand, enactment of the treaty was followed by a substantial drop in the atmospheric concentration of radioactive particles.
On the other hand,
nuclear proliferation
Nuclear proliferation is the spread of nuclear weapons, fissionable material, and weapons-applicable nuclear technology and information to nations not recognized as "Nuclear Weapon States" by the Treaty on the Non-Proliferation of Nuclear Weap ...
was not halted entirely (though it may have been slowed) and nuclear testing continued at a rapid clip. Compared to the 499 tests from 1945 to the signing of the PTBT, 436 tests were conducted over the ten years following the PTBT. Furthermore, US and Soviet underground testing continued "venting" radioactive gas into the atmosphere.
Additionally, though underground testing was generally safer than above-ground testing, underground tests continued to risk the leaking of
radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
s, including
plutonium
Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhib ...
, into the ground. From 1964 through 1996, the year of the CTBT's adoption, an estimated 1,377 underground nuclear tests were conducted. The final non-underground (atmospheric or underwater) test was conducted by China in 1980.
The PTBT has been seen as a step towards the
Nuclear Non-proliferation Treaty
The Treaty on the Non-Proliferation of Nuclear Weapons, commonly known as the Non-Proliferation Treaty or NPT, is an international treaty whose objective is to prevent the spread of nuclear weapons and weapons technology, to promote cooperation ...
(NPT) of 1968, which directly referenced the PTBT.
Under the NPT, non-nuclear weapon states were prohibited from possessing, manufacturing, and acquiring nuclear weapons or other nuclear explosive devices. All signatories, including nuclear weapon states, were committed to the goal of total
nuclear disarmament
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
* Nuclear space
* Nucle ...
. However, India,
Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
, and
Israel
Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
have declined to sign the NPT on the grounds that such a treaty is fundamentally discriminatory as it places limitations on states that do not have nuclear weapons while making no efforts to curb weapons development by declared nuclear weapons states.
In 1974, a step towards a comprehensive test ban was made with the
Threshold Test Ban Treaty (TTBT), ratified by the US and Soviet Union, which banned underground tests with yields above 150 kilotons.
In April 1976, the two states reached agreement on the
Peaceful Nuclear Explosions Treaty (PNET), which concerns nuclear detonations outside the weapons sites discussed in the TTBT. As in the TTBT, the US and Soviet Union agreed to bar
peaceful nuclear explosions
Peaceful nuclear explosions (PNEs) are nuclear explosions conducted for non-military purposes. Proposed uses include excavation for the building of canals and harbours, electrical generation, the use of nuclear explosions to drive spacecraft, and ...
(PNEs) at these other locations with yields above 150 kilotons, as well as group explosions with total yields over 1,500 kilotons. To verify compliance, the PNET requires that states rely on
national technical means of verification, share information on explosions, and grant on-site access to counterparties. The TTBT and PNET entered into force on 11 December 1990.

In October 1977, the US, UK, and Soviet Union returned to negotiations over a test ban. These three nuclear powers made notable progress in the late 1970s, agreeing to terms on a ban on all testing, including a temporary prohibition on PNEs, but continued disagreements over the compliance mechanisms led to an end to negotiations ahead of
Ronald Reagan's inauguration as president in 1981.
In 1985, Soviet leader
Mikhail Gorbachev announced a unilateral testing moratorium, and in December 1986, Reagan reaffirmed US commitment to pursue the long-term goal of a comprehensive test ban. In November 1987, negotiations on a test ban restarted, followed by a joint US-Soviet program to research underground-test detection in December 1987.
Negotiations
Given the political situation prevailing in the subsequent decades, little progress was made in nuclear disarmament until the end of the
Cold War in 1991. Parties to the PTBT held an amendment conference that year to discuss a proposal to convert the Treaty into an instrument banning all nuclear-weapon tests. With strong support from the UN General Assembly, negotiations for a comprehensive test-ban treaty began in 1993.
Adoption
Extensive efforts were made over the next three years to draft the Treaty text and its two annexes. However, the
Conference on Disarmament
The Conference on Disarmament (CD) is a multilateral disarmament forum established by the international community to negotiate arms control and disarmament agreements based at the Palais des Nations in Geneva. The Conference meets annually in ...
, in which negotiations were being held, did not succeed in reaching consensus on the adoption of the text. Under the direction of Prime Minister
John Howard
John Winston Howard (born 26 July 1939) is an Australian former politician who served as the 25th prime minister of Australia from 1996 to 2007, holding office as leader of the Liberal Party. His eleven-year tenure as prime minister is the ...
and Foreign Minister
Alexander Downer
Alexander John Gosse Downer (born 9 September 1951) is an Australian former politician and diplomat who was leader of the Liberal Party from 1994 to 1995, Minister for Foreign Affairs from 1996 to 2007, and High Commissioner to the United K ...
, Australia then sent the text to the
United Nations General Assembly
The United Nations General Assembly (UNGA or GA; french: link=no, Assemblée générale, AG) is one of the six principal organs of the United Nations (UN), serving as the main deliberative, policymaking, and representative organ of the UN. Cur ...
in
New York
New York most commonly refers to:
* New York City, the most populous city in the United States, located in the state of New York
* New York (state), a state in the northeastern United States
New York may also refer to:
Film and television
* '' ...
, where it was submitted as a draft resolution. On 10 September 1996, the Comprehensive Test-Ban Treaty (CTBT) was adopted by a large majority, exceeding two-thirds of the General Assembly's Membership.
Obligations
(Article I):
# Each State Party undertakes not to carry out any
nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...
test explosion or any other nuclear explosion, and to prohibit and prevent any such nuclear explosion at any place under its jurisdiction or control.
# Each State Party undertakes, furthermore, to refrain from causing, encouraging, or in any way participating in the carrying out of any nuclear weapon test explosion or any other nuclear explosion.
Status
The Treaty was adopted by the
United Nations General Assembly
The United Nations General Assembly (UNGA or GA; french: link=no, Assemblée générale, AG) is one of the six principal organs of the United Nations (UN), serving as the main deliberative, policymaking, and representative organ of the UN. Cur ...
on 10 September 1996.
It opened for signature in New York on 24 September 1996,
[United Nations Treaty Collection (2009). ]
Comprehensive Nuclear-Test-Ban Treaty
". Retrieved 23 August 2009. when it was signed by 71 states, including five of the eight then
nuclear-capable states. , 176 states have
ratified
Ratification is a principal's approval of an act of its agent that lacked the authority to bind the principal legally. Ratification defines the international act in which a state indicates its consent to be bound to a treaty if the parties inte ...
the CTBT and another 10 states have signed but not ratified it.
The treaty will enter into force 180 days after the 44 states listed in Annex 2 of the treaty have ratified it. These "Annex 2 states" are states that participated in the CTBT's negotiations between 1994 and 1996 and possessed nuclear power reactors or research reactors at that time. , eight Annex 2 states have not ratified the treaty: China, Egypt, Iran, Israel and the United States have signed but not ratified the Treaty; India, North Korea and Pakistan have not signed it.
Monitoring
Geophysical
Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...
and other technologies are used to monitor for compliance with the Treaty:
forensic seismology, hydroacoustics,
infrasound
Infrasound, sometimes referred to as low status sound, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz). Hearing becomes gradually less sensitive as frequency decreases, so for humans to perce ...
, and
radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...
monitoring. The first three forms of monitoring are known as
wave-form measurements. Seismic monitoring is performed with a system of 50 primary stations located throughout the world, with 120 auxiliary stations in signatory states. Hydroacoustic monitoring is performed with a system of 11 stations that consist of
hydrophone
A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potent ...
triads to monitor for underwater explosions. Hydroacoustic stations can use seismometers to measure T-waves from possible underwater explosions instead of hydrophones. The best measurement of hydroacoustic waves has been found to be at a depth of 1000 m. Infrasound monitoring relies on changes in atmospheric pressure caused by a possible nuclear explosion, with 41 stations certified as of August 2019. One of the biggest concerns with infrasound measurements is noise due to exposure from wind, which can affect the sensor's ability to measure if an event occurred. Together, these technologies are used to monitor the ground, water, and atmosphere for any sign of a nuclear explosion.
Radionuclide monitoring takes the form of either monitoring for radioactive particulates or
noble gas
The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low che ...
es as a product of a nuclear explosion. Radioactive particles emit radiation that can be measured by any of the 80 stations located throughout the world. They are created from nuclear explosions that can collect onto the dust that is moved from the explosion. If a nuclear explosion took place underground, noble gas monitoring can be used to verify whether or not a possible nuclear explosion took place. Noble gas monitoring relies on measuring increases in radioactive
xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
gas. Different isotopes of xenon include
131mXe,
133Xe,
133mXe, and
135Xe. All four monitoring methods make up the International Monitoring System (IMS). Statistical theories and methods are integral to CTBT monitoring providing confidence in verification analysis. Once the Treaty enters into force, on-site inspections will be conducted where concerns about compliance arise.
The
Preparatory Commission for the
Comprehensive Test Ban Treaty Organization (CTBTO), an international organization headquartered in
Vienna
en, Viennese
, iso_code = AT-9
, registration_plate = W
, postal_code_type = Postal code
, postal_code =
, timezone = CET
, utc_offset = +1
, timezone_DST ...
, Austria, was created to build the verification framework, including establishment and provisional operation of the network of monitoring stations, the creation of an international data centre (IDC), and development of the on-site Inspection capability. The CTBTO is responsible for collecting information from the IMS and distribute the analyzed and raw data to member states to judge whether or not a nuclear explosion occurred through the IDC. Parameters such as determining the location where a nuclear explosion or test took place is one of the things that the IDC can accomplish. If a member state chooses to assert that another state had violated the CTBT, they can request an on-site inspection to take place to verify.
The monitoring network consists of 337 facilities located all over the globe. As of May 2012, more than 260 facilities have been certified. The monitoring stations register data that is transmitted to the international data centre in Vienna for processing and analysis. The data are sent to states that have signed the Treaty.
Subsequent nuclear testing
Three countries have tested nuclear weapons since the CTBT opened for signature in 1996. India and Pakistan both carried out two sets of tests in 1998. North Korea carried out six announced tests, one each in 2006, 2009, 2013, two in 2016 and one in 2017. All six North Korean tests were picked up by the International Monitoring System set up by the Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission. A North Korean test is believed to have taken place in January 2016, evidenced by an "artificial earthquake" measured as a magnitude 5.1 by the
U.S. Geological Survey. The first successful North Korean hydrogen bomb test supposedly took place in September 2017. It was estimated to have an explosive yield of 120 kilotons.
See also
*
List of weapons of mass destruction treaties
*
Comprehensive Nuclear-Test-Ban Treaty Organization
*
Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission
*
National technical means of verification
*
Nuclear disarmament
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
* Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
* Nuclear space
* Nucle ...
*
Nuclear-free zone
*
Treaty on the Prohibition of Nuclear Weapons
References
Sources
*
*
*
*
*
*
*
*
*
*
External links
Full text of the treaty
CTBTO Preparatory Commissionnbsp;— official news and information
ABC News, 24 February 2006
*
ttps://www.armscontrol.org/factsheets/ctbtissue.asp Daryl Kimball and Christine Kucia, Arms Control Association, 2002General John M. Shalikashvili, Special Advisor to the President and the Secretary of State for the Comprehensive Test Ban TreatyChristopher Paine, Senior Researcher with NRDC's Nuclear Program, 1999Obama or McCain Can Finish Journey to Nuclear Test Ban Treatyon the ''Comprehensive Nuclear Test Ban Treaty'' in th
United Nations Audiovisual Library of International Lawtitled ''Nuclear Weapons and International Law'' in th
*
ttps://web.archive.org/web/20110303215535/http://opencrs.com/document/RL33548/ Comprehensive Nuclear-Test-Ban Treaty: Background and Current DevelopmentsCongressional Research Service
The Congressional Research Service (CRS) is a public policy research institute of the United States Congress. Operating within the Library of Congress, it works primarily and directly for members of Congress and their committees and staff on ...
The Woodrow Wilson Center's Nuclear Proliferation International History Projector NPIHP is a global network of individuals and institutions engaged in the study of international nuclear history through archival documents, oral history interviews and other empirical sources.
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