Why did truman decide to use the atomic bomb?

For Truman, the choice whether or not to use the atomic bomb was the most difficult decision of his life. First, an Allied demand for an immediate unconditional surrender was made to the leadership in Japan. Although the demand stated that refusal would result in total destruction, no mention of any new weapons of mass destruction was made. read more

President Truman decided to use the bomb for many reasons. Having not knowledge about the existence of the bomb until his presidency, he saw it as a new weapon developed by the US and that should be used for that purpose. Secondly, Truman wanted to avoid an invasion of Japan because it would be extremely costly, difficult, and simply horrible. read more