olivant:

"The surrender by the Japanese Cabinet and Hirohito was more than likely based on the proximate devastation wrought by the atomic bombs on the Japanese homeland and not the Soviet's near destruction of the Japanese Kwamtung army in far-away China."

I once saw a picture of Tokyo after the March 1945 firebombing. Next to it was one of Hiroshima after the atomic bombing. The two cities didn't look a lot different.