What is this I keep hearing about the US only having the two atomic bombs? Even while the US was bombing it was producing more atomic cores for a sustained atomic bombing effort if Japan failed to surrender. The next one was scheduled to be shipped from Los Alamos and arrive for use against Japan on August 17 or 18. There was a whole list of potential targets. The leaflets were deployed after the first atomic bomb was dropped warning other Japanese cities to evacuate. The leaflets scheduled for Nagasaki didn't get their until August 10 which would have been before the original schedule for bombing but the schedule was moved up due to bad weather forcasts, and of course Nagasaki was the backup target. The primary target had been the Kokura Arsenal however weather prevented the bombing of that target and Nagasaki was the only backup target which weather permitted the bombing of.
I won't go into the morality of the use of atomic bombs on Japan. Or the morale justification for the Japanese release of the first modern bio weapons over China etc... etc...
A timeline:
http://vikingphoenix.com/public/Japa...5/abombchr.htm
Japanese Bio Weapons:
http://www.fas.org/nuke/guide/japan/bw/