It is surprising to see some conservatives cheering Truman's needless, barbaric nuking of anti-communist Japan. Japan did not "mess with America." FDR refused Japan's reasonable peace offers and provoked Japan to attack Pearl Harbor so he could enter WW II and save his beloved Soviet Union. FDR's and Truman's administrations were heavily penetrated with Soviet spies and sympathizers. A top Soviet policy goal was war between America and Japan, and FDR's disastrous pro-Soviet foreign policy toward Japan played a key role in making that goal become tragic reality.
There was absolutely no need to nuke Japan. Japan was prostrate, starving, and was virtually defenseless against air and naval attack.. Truman knew that most of Japan's leaders, including the emperor, wanted to end the war and were willing to surrender on very reasonable terms.