Vela Incident

Out of over 2000+ nuclear test detonations that have taken place on earth, only one has an unknown nationality. On September 22, 1979, the Vela satellite reported the characteristic double flash (a very fast and very bright flash, then a longer and less-bright one) of an atmospheric nuclear explosion of two to three kilotons, in the Indian Ocean between Bouvet Island (Norwegian dependency) and the Prince Edward Islands (South African dependencies). US Airforce planes flew into the area shortly but could find no signs of a detonation or radiation.