Firstly, we should understand that America's bombing of Hiroshima and Nagasaki was politically motivated, but the motive was different to what they claimed. Officially, US Government claimed that the atomic bombing of Hiroshima/Nagasaki was precipitated by a desire to force a Japanese surrender without a great loss of life, which would inevitably ensue in the event of invading the Japanese mainland. What they claim is one thing; but the reality is quite different. The atomic bombing of Hiroshima was in part racially motivated in retaliation for Japanese atrocities committed against Allied civilians as well as military personnel during the War in the Pacific, 1941-1945. U.S. and it's allies abhor atrocities committed by Japanese soldiers, which is a form of reverse discrimination against White people. Naturally, the U.S. Government had nothing but a moral duty to rectify this reversal of positions whereby White people have been victimized for the first time since the 13th Century when the Mongols decimated European populations in Central and Eastern Europe. White people have been the global top dogs for the last 500 years at least; and it was the U.S. Government's intention to reassert the status quo by making a very clear message to the Japanese people as well as the international community.
Whereas, in the case of Nazi Germany the Americans would NEVER use atomic weapons because such a power relationship has never existed between different groups of White people. In the case of Germany, Harry Truman would never push the button because the Americans would never kill their own people.
