How did Truman justify the United States' atomic bombing of Japan?

Answer 1

At the time, no one questioned it. Hundreds of cities had been bombed to ruins during the preceding six years, and millions of civilians killed in the process. The atomic missions did end the war, and all the Allies were exceedingly glad of it - except perhaps the Russians, who only got into the war against Japan for the last week, and would have liked more time to gobble up more Japanese territory. Even the Japanese were not too upset over it, since they had a more pressing thing to worry about, which was just having lost the war of aggression they had started. The Japanese were more worried about getting to keep their Emperor, whom they believed was a living god. Anyone in an American uniform at the time thought the bombs were just absolutely beautiful, because now they would not have to die invading Japan, and they could go home.

The bombs actually saved many more lives than they snuffed out. There was detailed planning underway for the first two of a planned four invasion landings of the Japanese Home Islands. Estimates were that in the first of these alone, there would be one million American casualties. And it was assumed that ALL the Japanese would have to be killed. Certainly all the military men, and probably the civilians too. The Japanese were drilling women with bamboo spears and planned to send them out to try to stab Americans when the landings came. The US had just finished the capturing of Iwo Jima and Okinawa, and as in every earlier battle of the Pacific, the Japanese had fought to the last man, long, long after it was hopeless. It was expected they would be even more fanatical in their own Home Islands.

In deciding on using the bombs Truman had to consider that if he did not use them, when it became known that the US had invested over one billion 1940 dollars (probably equal to 100 billion today) in a weapon that could have immediately ended the war, but instead Truman had decided NOT to use it and had sent millions of Americans to die or be permanently crippled and maimed capturing Japan, that the people of the US would demand his head on a platter.

Answer 2

Ending thw war sooner and saving tens of thousands of Allied and Japanese lives......