TTBT: Threshold Test Ban Treaty

Executive Summary

Treaty/Program Name:

Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Underground Nuclear Weapons Tests and the Protocol [Verification] to the Treaty between the United States of America and the Union of Soviet Socialist Republics on the Limitation of Underground Nuclear Weapons Tests

Brief Description:

The Threshold Test Ban Treaty (TTBT) was signed in Moscow on 3 July 1974, and its verification Protocol was signed in June 1990. The TTBT prohibits tests with a yield greater than 150 kilotons (KT). Its verification Protocol allows the parties to measure the yields of nuclear tests, using either the hydrodynamic yield measurement method, the seismic yield measurement method, or on-site inspections (OSI). OSI can be used to monitor any test with a planned yield in excess of 35 KT. The Treaty also requires data exchanges in order to allow each side to calibrate equipment for measuring yields of nuclear tests.

In October 1991, the USSR declared a one-year moratorium on nuclear testing. Russian Federation President Boris Yeltsin continued this moratorium and extended it indefinitely. Similarly, President Bush signed legislation in October 1992 that declared a moratorium on U.S. nuclear tests. This legislation, sponsored by Senators Hatfield, Exon, and Mitchell, halted U.S. nuclear testing through July 1993. Subsequently, President Clinton has renewed this moratorium, and has declared that, pending the conclusion of negotiations on a treaty banning all tests, the U.S. will not conduct any more nuclear weapon tests.


In August 1995, President Clinton announced that the United States would pursue negotiation of a zero-yield Comprehensive Test Ban Treaty (see separate entry). In his statement, the President declared that "the United States will insist on a test ban that prohibits any nuclear weapons test explosion, or any other nuclear explosion." However, the President also stated that the United States would reserve the right to resume testing if the safety and reliability of the nuclear stockpile could no longer be certified without tests.


France and China also support the negotiation of a comprehensive test ban; however, neither state is observing the testing moratorium. China's most recent test occurred at the Lop Nur test facility in August 1995, while France has conducted six tests at their South Pacific test site at Muroroa since September 1995. The last French test occurred on 27 January 1996.


Negotiation Status/Signatories:

Signed: 03 July 1974 (Treaty)
01 June 1990 (Protocol)
Ratification: 11 December 1990
Entry Into Force (EIF): 11 December 1990
Duration: 5 years, with 5 year extensions

Parties:

  • United States
  • USSR (RF assumes successor state status)

Systems/Items Involved:

  • Underground Nuclear Tests in the U.S. and the former USSR

Monitoring:

  • What:
    • The yields of underground nuclear weapons detonations.

  • Where:
    • At only the following test sites:
      • U.S.: Nevada Test Site
      • USSR: The Northern Test Site (Novaya Zemlya, now located in the RF); and Semipalatinsk Test Site (Now located in Kazakstan). This site has been essentially shut down.

  • How:
    • National Technical Means:
    • Inspection using either of the following methodologies:
      • Hydrodynamic Yield Measurement;
      • Hydro plus Yield Measurement;
      • Seismic Yield Measurement; and
      • On-site Inspection.

Service/DoD Implementation Responsibilities:

  • Air Force:
    • Underground weapons tests no greater than 150 KT; inspections at the Nevada Test Site (with DoE).

  • Army:
    • Underground weapons tests no greater than 150 KT; inspections at the Nevada Test Site (with DoE).

  • Navy:
    • Underground weapons tests no greater than 150 KT; inspections at the Nevada Test Site (with DoE).

  • On-Site Inspection Agency (OSIA):
    • Overall responsibility for former Soviet inspections in the U.S. and U.S. inspections in the former USSR.

  • DoE/Labs:
    • Overall responsibility for nuclear weapons testing and inspections at the Nevada Test Site.

  • Defense Nuclear Agency (DNA):
    • Responsibility for measurement of tunnel tests in vertical shafts by the "Hydro Plus" technique.


Implementation and Compliance Body:

  • The Bilateral Consultative Commission (BCC).

Communications Means:

  • Nuclear Risk Reduction Centers (NRRC) in the U.S. and the Russian Federation.

Current Issues/Activities:

  • With the moratorium on all nuclear testing in effect for the Parties to this Treaty and the prospects for the signing of a multilateral CTBT in 1996, there are no major issues regarding the TTBT.

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