The morality and utility of nuclear weapons have been debated passionately since their creation. Trinity, the first atomic detonation in 1945, vividly demonstrated the awesome destructive power of this technological leap. The explosion, which Manhattan Project’s chief scientist Robert Oppenheimer described in apocalyptic terms, had an instant impact on the bomb’s creators, several of whom would later question the wisdom of developing the weapon even though it had been designed and employed to end a conventional war that claimed the lives of tens of millions. At the time, no one disputed that the destruction of Hiroshima and Nagasaki had had a decisive impact on the Japanese leadership’s decision to end the war, thereby saving a million or more American and Japanese lives. But neither did anyone relish a future in which the use of nuclear weapons would become an accepted condition of warfare.