No and yes
There were no remaining Japanese military bases. We had either already bombed them, or they had dispersed or disguised them so we wouldn't. As one Army Air Corps official put it, "There are no more targets".
I call Bullshit. If there were no military targets we could have walked in unopposed. There had to be at least a large concentration of military forces on mainland Japan we could have targeted.
By the time we made the nuclear decision... We were in no mood to be merciful.
THAT was the reason entirely why we nuked civilian cities with no military value.