Evidence

     Dropping the two atomic bombs was the justified choice because the other option was invading Japan. Casualties were estimated to be about one million American soldiers and half a million British soldiers in the first invasion alone. The Allies warned the Axis of powers, in the pacific theater, that if they didn't surrender there would be prompt utter destruction. The Japanese wouldn't surrender, so harry Truman decided to drop the first bomb "Little Boy" on Hiroshima. Even then the Japanese wouldn't surrender. So then we we dropped the second bigger bomb "Fat Man" on Nagasaki, the Japanese surrendered after that.
       Some people say dropping the bombs was unnecessary from a military perspective because Japan was defeated and ready to surrender. Japan may have been near defeat but we warned them before we dropped the bombs to surrender but they said they would fight until the end, and even after we dropped the first bomb on Hiroshima they still would not surrender. Then we dropped the second one on Nagasaki and the emperor decided to surrender, but there still military officials who thought they should keep fighting. So I would think they Japanese may have been defeated but not close to surrendering.