List of nuclear weapons tests

Nuclear weapons testing is the act of experimentally and deliberately firing one or more nuclear devices in a controlled manner pursuant to a military, scientific or technological goal. This has been done on test sites on land or waters owned, controlled or leased from the owners by one of the eight nuclear nations: the United States, the Soviet Union, the United Kingdom, France, China, India, Pakistan and North Korea, or has been done on or over ocean sites far from territorial waters. There have been 2,121 tests done since the first in July 1945, involving 2,476 nuclear devices. As of 1993, worldwide, 520 atmospheric nuclear explosions (including eight underwater) have been conducted with a total yield of 545 megatons (Mt): 217 Mt from pure fission and 328 Mt from bombs using fusion, while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992 is 1,352 explosions with a total yield of 90 Mt. As a result of the 1996 Comprehensive Nuclear-Test-Ban Treaty, there were no declared tests between the 1998 Pakistani Chagai-II and the 2006 North Korean test, and none outside North Korea to date. Very few unknown tests are suspected at this time, the Vela incident being the most prominent. Israel is the only country suspected of having nuclear weapons but not confirmed to have ever tested any. The following are considered nuclear tests:

Single nuclear devices fired in deep horizontal tunnels (drifts) or in vertical shafts, in shallow shafts ("cratering"), underwater, on barges or vessels on the water, on land, in towers, carried by balloons, shot from cannons, dropped from airplanes with or without parachutes, and shot into a ballistic trajectory, into high atmosphere or into near space on rockets. Since 1963 the great majority have been underground due to the Partial Test Ban Treaty. Salvo tests in which several devices are fired simultaneously, as defined by international treaties: In conformity with treaties between the United States and the Soviet Union, ... For nuclear weapon tests, a salvo is defined as two or more underground nuclear explosions conducted at a test site within an area delineated by a circle having a diameter of two kilometers and conducted within a total period of time of 0 seconds. The two nuclear bombs dropped in combat over Japan in 1945. While the primary purpose of these two detonations was military and not experimental, observations were made and the tables would be incomplete without them. Nuclear safety tests in which the nuclear yield was intended to be zero, and which failed to some extent if a nuclear yield was detected. There have been failures, and therefore they are included in the lists, as well as the successes. Fizzles, in which the expected yield was not reached. Tests intended but not completed because of vehicle or other support failures that destroyed the device. Tests that were emplaced and could not be fired for various reasons. Usually, the devices were ultimately destroyed by later conventional or nuclear explosions. Not included as nuclear tests:

Misfires which were corrected and later fired as intended. Hydro-nuclear or subcritical testing in which the normal fuel material for a nuclear device is below the amount necessary to sustain a chain reaction. The line here is finely drawn, but, among other things, subcritical testing is not prohibited by the Comprehensive Nuclear Test Ban Treaty, while safety tests are.