Nuclear Testing History
From atmospheric detonations to underground tests, how over 2,000 nuclear explosions shaped arms races, contaminated communities, and eventually led to test ban treaties.
The Testing Era
Between 1945 and 1996, the world's nuclear powers conducted over 2,000 nuclear test explosions. The United States conducted 1,032 tests, the Soviet Union 715, France 210, the United Kingdom 45, and China 45. Early tests were atmospheric: bombs detonated in the open air, on barges, on towers, or dropped from aircraft. The most powerful test in history was the Soviet Union's Tsar Bomba in 1961, a hydrogen bomb that yielded 50 megatons, roughly 3,000 times the Hiroshima bomb.
Testing served multiple purposes. It validated new weapon designs, demonstrated capability to adversaries, and trained military personnel. But it also caused enormous environmental and health damage. Atmospheric tests spread radioactive fallout across the globe. The US Castle Bravo test at Bikini Atoll in 1954, which was 2.5 times more powerful than expected, contaminated the crew of the Japanese fishing vessel Lucky Dragon No. 5 and the inhabitants of several Marshall Islands atolls with deadly radiation.