Vela incident

The Vela incident was an atmospheric nuclear explosion that occurred on 22 September 1979, near the South African territory of Prince Edward Islands in the Indian Ocean, roughly midway between Africa and Antarctica. This explosion is widely believed to have been an undeclared test of an Israeli nuclear weapon on the ocean surface, carried out with assistance from South Africa. Initially detected as a double flash of light by an American Vela Hotel satellite, further meteorological satellite, hydroacoustic, and radionuclide data support the event's identification as an atmospheric nuclear explosion.

Most historians conclude that Israel tested a low-yield nuclear device, around two to three kilotons of TNT, and that the United States subsequently attempted a cover-up. Historians have pointed to the test's timing with a typhoon in the region and no overhead Vela satellites which were listed as active, the receiving satellite being listed as retired. In 1980, US President Jimmy Carter wrote in his diary, "We have a growing belief among our scientists that the Israelis did indeed conduct a nuclear test explosion in the ocean near the southern end of Africa." Experts have suggested the weapon tested was a neutron bomb and/or nuclear artillery round, and that Israel may have carried out other nuclear tests.

If an atmospheric nuclear explosion, it was the second most recent in history, preceding an October 1980 nuclear weapons test by China. If conducted by Israel, it was in contravention of Israel's 1964 ratification of the Partial Nuclear Test Ban Treaty.

The previous 41 double flashes detected by the Vela satellites were caused by atmospheric nuclear tests. Some traces of potential nuclear fallout were detected in Australia but not New Zealand. Some information about the event remains classified by the United States government. Its Department of Defense initially suggested a combination of phenomena such as lightning and a meteoroid hitting the satellite.