Professor Richard B. Frank analyzes the facts that annihilate the arguments against dropping the atomic bomb on Japan in 1945. From his Weekly Standard article (linked in title):
The critics [of Truman's decision to authorize dropping the A-bomb on Hiroshima and Nagasaki] share three fundamental premises. The first is that Japan's situation in 1945 was catastrophically hopeless. The second is that Japan's leaders recognized that fact and were seeking to surrender in the summer of 1945. The third is that thanks to decoded Japanese diplomatic messages, American leaders knew that Japan was about to surrender when they unleashed needless nuclear devastation. The critics divide over what prompted the decision to drop the bombs in spite of the impending surrender, with the most provocative arguments focusing on Washington's desire to intimidate the Kremlin. Among an important stratum of American society--and still more perhaps abroad--the critics' interpretation displaced the traditionalist view.
All three premises are incorrect, as Frank demonstrates in a lengthy and interesting article that proves his central conclusion:
. . . [I]t is clear that all three of the critics' central premises are wrong. The Japanese did not see their situation as catastrophically hopeless. They were not seeking to surrender, but pursuing a negotiated end to the war that preserved the old order in Japan, not just a figurehead emperor. Finally, thanks to radio intelligence, American leaders, far from knowing that peace was at hand, understood--as one analytical piece in the "Magic" Far East Summary stated in July 1945, after a review of both the military and diplomatic intercepts--that "until the Japanese leaders realize that an invasion can not be repelled, there is little likelihood that they will accept any peace terms satisfactory to the Allies." This cannot be improved upon as a succinct and accurate summary of the military and diplomatic realities of the summer of 1945.
Read it all.