Nuclear weapons testing: The United States successfully detonates Ivy Mike, the first thermonuclear device, at the Eniwetok atoll. The explosion had a yield of ten megatons TNT equivalent.

Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Over 2,000 nuclear weapons tests have been carried out since 1945. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Because of their destruction and fallout, testing has seen opposition by civilians as well as governments, with international bans having been agreed on. Thousands of tests have been performed, with most in the second half of the 20th century.