Between the Trinity nuclear test of 16 July 1945 and the signing of the Partial Test Ban Treaty ( PTBT ) on 5 August 1963 , 499 nuclear tests were conducted . Much of the impetus for the PTBT , the precursor to the CTBT , was rising public concern surrounding the size and resulting nuclear fallout from underwater and atmospheric nuclear tests , particularly tests of powerful thermonuclear weapons ( hydrogen bombs ) . The Castle Bravo test of 1 March 1954 , in particular , attracted significant attention as the detonation resulted in fallout that spread over inhabited areas and sickened a group of Japanese fishermen . Between 1945 and 1963 , the US conducted 215 atmospheric tests , the Soviet Union conducted 219 , the UK conducted 21 , and France conducted three
Trinity nuclear test
Trinity (nuclear test)
Comprehensive Nuclear-Test-Ban Treaty