Nuclear explosion debris. The first man made nuclear explosion occurred on July 16, 1945 at 5:50 am on the Trinity Test Site near Alamogordo, New Mexico in the United States, an area now known as the White Sands Missile Range. The event involved the full-scale testing of an implosion-type fission atomic bomb. In a memorandum to the U.S. Secretary of War, General Leslie Groves describes the yield as equivalent to 15,000 to 20,000 tons of TNT. Following this test, a uranium-gun type nuclear bomb (Little Boy) was dropped on the Japanese city of Hiroshima on August 6, 1945, with a blast yield
Strategic Air Command in the United Kingdom that a B-29 over the north Pacific Ocean had observed a large radiation cloud. Analysis showed that this cloud was from an atomic explosion on the Asian mainland sometime between 26 and 29 August. The Soviet Union had the atom bomb, far earlier than the United States expected it. The atomic umbrella which the B-29s and B-50s brought to Western Europe consisted of just thirty atom bombs, probably stored in West Germany or England. In 1948, there were only 32 B-29s converted to carry nuclear weapons. With the Soviet Union having the atomic bomb, American strategy had to be changed