Treaty Banning Nuclear Tests in the Atmosphere, in Outer Space and Under Water (Partial Test Ban Treaty) (PTBT)

Note: As of February 2008, this page will no longer be updated.


  • Opened for signature: 5 August 1963
  • Entered into force: 10 October 1963
  • Duration: The Treaty is of unlimited duration
  • Number of Parties
  • Depositories: Russia, United Kingdom, and United States



In 1954, India made the first proposal calling for an agreement to ban nuclear weapons tests. In 1958, the United States, the Soviet Union, and the United Kingdom began a Conference on the Discontinuance of Nuclear Tests in Geneva, aimed at reaching agreement on an effectively controlled test ban. The Conference did not come to fruition because the sides could not reach an agreement on the issue of verification procedures. On 5 August 1963, the Partial Test Ban Treaty (PTBT) — also known as the Limited Test Ban Treaty (LTBT) — was signed in Moscow by the United States, the Soviet Union, and the United Kingdom.

Treaty Obligations

The Treaty requires Parties to prohibit, prevent, and abstain from carrying out nuclear weapons tests or any other nuclear explosions in the atmosphere, in outer space, under water, or in any other environment if such explosions cause radioactive debris to be present outside the territorial limits of the State that conducts an explosion; 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, anywhere which would take place in any of the above-described environments.

Verification and Compliance

The PTBT does not provide for international verification; however, it is understood that each party may do so by its own national technical means.



With the signing of the Comprehensive Test Ban Treaty (CTBT) in September 1996, the PTBT became redundant. However, should a PTBT party withdraw from the CTBT, or not sign the CTBT, it would still be bound by the provisions of the PTBT.


The UN General Assembly (UNGA) passed resolution 50/64 urging the conclusion of the CTBT and urged all States not already doing so to adhere to the PTBT.


The 1994 session of the UN General Assembly noted that the Conference on Disarmament (CD) had initiated the multilateral negotiation of a universal and effectively verifiable CTBT. It took note of the intention of the President of the Amendment Conference to convene, after appropriate consultations, and in the light of the work carried out by the CD, another special meeting of the States Parties to the PTBT, to review developments and assess the situation regarding a CTBT, and to examine the feasibility of resuming the work of the Amendment Conference.


On 10 August, a special meeting of the States Parties to the PTBT was held. Broad agreement was found for pursuing work on a CTBT in the Amendment Conference and in the CD "in a mutually supportive and mutually complimentary manner," for holding another special meeting early in 1994; and for promoting the universality of a CTBT by having the President of the Amendment Conference liaise with the CD and the five nuclear weapon States (NWS).

1991 and 1992

The Amendment Conference was held in New York from 8-18 January 1991, but ended in deadlock. However, Indonesian Foreign Minister Ali Alatas was mandated to continue consultations. In 1991 and 1992, the UNGA called for resumption of the negotiations as soon as possible.


On 5 August, five nations asked the PTBT depository States to circulate a call for an Amendment Conference with the aim of reaching an agreement on a CTBT.


In 1982, the United States announced that it would not resume trilateral efforts, but would pursue the Threshold Test Ban Treaty (TTBT) and Peaceful Nuclear Explosions Treaty (PNE) and discussions in the CD working group.


On 3 October, the United States, United Kingdom, and the Soviet Union resumed trilateral negotiations on a CTBT.


The PTBT requires parties to abstain from carrying out nuclear explosions in any environment where such explosions cause radioactive debris outside the limits of the State that conducts an explosion.

This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents. Copyright 2019.