The irony of 1945...

...is that the USA knew that Japan was willing to surrender with the only condition to retain the monarchy, that is, exactly what it got in the end. Since the European theater had already been won, the real reason for the bomb was to warn the Soviet Union of the capabilities of the USA. Something the Soviet Union already knew anyway through moles, even if they were still years away from developing a bomb of their own.

Although honestly that may have prevented USSR intervention in Japan itself and prevented a nuclear escalation in the China, Korea and Vietnam, so... Stalin was a psycho too, who didn't hesitate to genocide Soviet citizens, murder real or imaginary opponents, or use all sorts of brutality in WW2 and send millions of his own soldiers, officers and civilians to die in it. He and the rest of the Soviet leadership at least had a self preservation instinct though. At the moment I am doubting Putin does.