To what extent was the use of the atomic bomb justified? Did Truman have a good enough excuse to do so?
Historians have long debated whether the use of the atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August of 1945 was justified, and Truman clearly struggled to make the decision to drop the bombs. He had offered Japan an opportunity for unconditional surrender, but they had refused. At the time, the Americans warned Japan that they would face destruction if they did not surrender, though the U.S. did not tell the Japanese about the atomic bombs in advance. In addition, the U.S. had taken over the islands of Iwo Jima and Okinama, but the Japanese did not cede these islands without a fierce fight. Many Japanese preferred death over surrender, and the fighting on these islands had been very deadly.
The Americans' reasons to drop the bomb may have been manifold. First, they wanted to end the long war quickly and spare the thousands, if not hundreds of thousands, of American lives that would have been lost if the U.S. had mounted an amphibious assault on Japan. While estimates vary, it is clear that many American soldiers would have died if they had attacked Japan. This has been given as the main compelling reason for Truman to drop the bombs.
On the other hand, other historians argue that Truman may have dropped the bomb for ulterior motives, including scaring the Soviet Union, who had already occupied parts of Eastern Europe and who was shaping up to be the post-war American adversary. In addition, Truman may have wanted to justify the cost of the Manhattan Project, the massive project to produce the atomic bombs, which was very expensive. Finally, perhaps Truman may have wanted to get back at Japan for having bombed Pearl Harbor in 1941. These ulterior motives are not considered as compelling as Truman's stated goal to spare American lives. The bombs resulted in the loss of hundreds of thousands of Japanese lives immediately and the eventual loss of countless lives as a result of radiation poisoning. The debate about whether Truman was justified in dropping the bombs is a difficult one with compelling arguments on both sides.