Nuclear technology the element plutonium possesses an isotope that is sufficiently unstable for this process to be usable. Terrestrial plutonium does not currently occur naturally in sufficient quantities for such use, so it must be manufactured in a nuclear reactor. Ultimately, the Manhattan Project manufactured nuclear weapons based on each of these elements. They detonated the first nuclear weapon in a test code-named "Trinity", near Alamogordo, New Mexico, on July 16, 1945. The test was conducted to ensure that the implosion method of detonation would work, which it did. A uranium bomb, Little Boy, was dropped on the Japanese city Hiroshima on
B61 nuclear bomb Mod 12. With reductions planned of nuclear weapons in Europe, which may retire the older Mod 3 and 4 and the Mod 10 already slated for retirement, and the possibility that European nations may not build or procure new aircraft to carry the Mod 12 would eliminate the need for consolidation into a new type. While the B83 nuclear bomb is not as old as the B61, the Pentagon sees it as a "relic of the Cold War," believing that deploying a megaton-yield gravity bomb, the highest level nuclear weapon left in the U.S. inventory, to Europe is "inconceivable" at