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Formal Title: TREATY ON THE LIMITATION OF UNDERGROUND NUCLEAR WEAPONS TESTS
Summary:
The Threshold Test Ban Treaty (TTBT) established a nuclear testing "threshold," by prohibiting tests having a yield exceeding 150 kilotons (equivalent to 150,000 tons of TNT). The threshold is militarily important since it removes the possibility of testing new or existing nuclear weapons going beyond the fractional-megaton range. Parties to the TTBT also undertook an obligation to continue negotiations toward a Comprehensive Test Ban Treaty (CTBT).
Agreement on the TTBT was reached during the summit meeting in Moscow in July 1974. The treaty included a protocol, which detailed the technical data that had to be exchanged and limited weapon testing to specific designated sites to assist verification. The data to be exchanged included information on the geographical boundaries and the geology of the testing areas. (Geological data is useful in verifying test yields because the seismic signal produced by a given underground nuclear explosion varies with the geography of the test location.) The TTBT also stipulated that data be exchanged on a certain number of tests for calibration purposes, which improved assessments by other parties of the yields of explosions based primarily on the measurements derived from their seismic instruments.
Although the TTBT was signed in 1974, it was not sent to the US Senate for ratification until July 1976. Submission was held up until the companion Peaceful Nuclear Explosions Treaty (PNET) had been successfully negotiated.
For many years, neither the United States nor the Soviet Union ratified the TTBT or the PNET. However, in 1976 each party separately announced its intention to observe the TTBT limit of 150 kilotons, pending ratification.
The United States and the Soviet Union began negotiations in November 1987 to reach agreement on additional verification provisions that would make it possible for the United States to ratify the treaties. Agreement on additional verification provisions, contained in new protocols, substituting for the original protocols, was reached in June 1990, and the TTBT and PNET entered into force on 11 December 1990.
For more in-depth information, please consult the Inventory of Nonproliferation Organizations and Regimes, which can be found on the CNS website at: http://cns.miis.edu/pubs/.
China and the TTBT:
China is not a signatory to the TTBT, a trilateral agreement between the United States, Soviet Union, and United Kingdom. However, China has been in de facto compliance with the TTBT since its 660 kT underground test on 21 May 1992.
For more background information, see:
[CHINA AND THE PEACEFUL NUCLEAR EXPLOSIONS TREATY (PNET)]
For more on China's nuclear testing program, see:
[CHINA'S NUCLEAR TESTING PROGRAM]
[CHRONOLOGY OF TESTING-RELATED STATEMENTS AND DEVELOPMENTS]
Other international nuclear testing treaties:
[CHINA AND THE COMPREHENSIVE TEST BAN TREATY (CTBT)]
[CHINA AND THE PARTIAL TEST BAN TREATY (PTBT)]
Last Updated June 1998
This
material is produced independently for NTI by the James Martin
Center for Nonproliferation Studies at the Monterey Institute of
International Studies and does not necessarily reflect the
opinions of and has not been independently verified by NTI or
its directors, officers, employees, agents. Copyright © 2007 by
MIIS.
