Threshold Test Ban Treaty (TTBT)

Signed: 1974

Ratified: 1990

Senate Ratification Vote: 98-0

Tsar Bomba is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated.The Threshold Test Ban Treaty (TTBT) established a nuclear “threshold” or limit, by prohibiting tests having a yield exceeding 150 kilotons. The threshold is important since it removes the possibility of testing new or existing nuclear weapons going beyond the fractional-megaton range. In the 1960s, many tests above 150 kilotons were conducted by both countries. The mutual restraint imposed by the Treaty reduced the explosive force of new nuclear warheads and bombs which could otherwise be tested for weapons systems. The TTBT verification protocol included seismic monitoring and on-site inspection for specific tests. Successful negotiations of the TTBT established mechanisms and methods which were important in the subsequent creation of the even more vital, but not yet ratified, Comprehensive Nuclear Test Ban Treaty.

Primary Source: U.S. State Department

Full Text of TTBT Treaty

Video on the Tsar Bomb Test

TTBT Lessons on Future Treaties

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