The first atomic detonation. Oppenheimer recalls his impressions of the moment for an interview on NBC in 1965.
The first nuclear weapon test was carried out by the United States at the Trinity site on July 16, 1945, with a yield approximately equivalent to 20 kilotons. The first hydrogen bomb, codenamed “Ivy Mike”, was tested at the Enewetak atoll in the Marshall Islands in November 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, many (but not 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. Neither has ever signed the treaty.
The United States conducted its last underground test in 1992, the Soviet Union in 1990, the U.K. in 1991, and both China and France in 1996. After signing the Comprehensive Test Ban Treaty in 1996 (which has as of 2012 not yet entered into force), all these states have pledged to discontinue all nuclear testing. Non-signatories India and Pakistan last tested nuclear weapons in 1998. The most recent nuclear test was by North Korea on Feb. 12, 2013.
For a more detailed resource on the history of Nuclear testing, see this United Nations guide,released August 29, 2012, the official ‘International Day Against Nuclear Tests’.