Now an ethnically Japanese historian who works in the United States, Tsuyoshi Hasegawa, has come up with yet another argument. He believes the war ended because of the Soviet Union's last-minute declaration of war against Japan and attack upon their forces in Manchuria. The viewpoint is explained in an article by Gareth Cook in The Boston Globe.
The article emphasizes something rarely discussed in this literature: nukes weren't so very much worse than massive fire bomb raids on Tokyo and elsewhere, at least in the short run. I believe the comparison was true, before long term radiation damage could manifest itself.
Was President Harry S. Truman right to order the use of the atom bombs? Given the information he had, yes, certainly. Second-guessing history is a mug's game.