History of Nuclear Weapons Testing

The first nuclear weapon was detonated as a test by the United States at the Trinity Site on July 16, 1945, with a yield approximately equivalent to 20kilotons. The first hydrogen bomb, codenamed "Mike", was tested at the Enewetak atoll in theMarshall Islands on November 1 (local date) in 1952, also by the United States. The largest nuclear weapon ever tested was the "Tsar Bomba" of the Soviet Union at Novaya Zemlya on October 30, 1961, with an estimated yield of around 50 megatons.

In 1963, all nuclear and many non-nuclear states signed the Limited Test Ban Treaty, pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space. The treaty permitted underground nuclear testing. France continued atmospheric testing until 1974, China continued up until 1980.

Underground tests in the United States continued until 1992 (its last nuclear testing), the Soviet Union in 1990, the United Kingdom in 1991, and both China and France in 1996. After signing the Comprehensive Test Ban Treaty(CTBT)  in 1996 (which has as of 2011 not yet entered into force), all of these states have pledged to discontinue all nuclear testing.