To most Americans at the end of 1945, the question of whether the dropping of the atomic bombs on Japan was justified or unconscionable was probably one that hardly needed to be asked. After years of desperate war, beginning with what almost all Americans viewed as a treacherous attack on Pearl Harbor (Roosevelt) and proceeding through island battles with appalling American casualties, and even greater Japanese casualties, as at Iwo Jima, where more Americans died than in the Normandy landings (Connor, p. 283). It was seriously anticipated that an invasion of Japan itself might cost more American lives than the whole previous war in Europe and Asia, two atomic bombs were dropped -- and Japan surrendered in a few days. The bombs had brought victory and peace; that must have seemed justification enough.
Only in later years were many questions raised, and these came amid changed circumstances. The fear of general nuclear annihilation lurked for a generation and more, while a military and political debacle in Vietnam raised doubts about the Cold War against communism, a Cold War that itself highlighted the nuclear spectre, and which was already incipient in the last weeks of the Second World War, when the atomic bombs were dropped on Japan. In this new light, a skepticism about the atomic bombings grew up, exemplified by Gar Alperovitz' article.
Alperovitz makes two arguments: first that Japan was already on the point of surrender, and second that even if they were not, they would have been driven to surrender by the imminent entry of the Soviet Union into the Pacific war. The latter is the one on which Alperovitz lays greater emphasis, the implication being that the atomic bombings were intended largely as a diplomatic shot across the Soviets' bows, and to forestall a Soviet claim to a share in victory against Japan.
However, a central fact of the prospective Soviet entry into the war against Japan is that it could ...