There's a lot in the FAQ about Hiroshima and Nagasaki. The notion that there was a weighty "decision" is historically fallacious — it was a linkage of small decisions over time rather than one big "decision" to use or not use the bomb (the notion that there was a big "decision" was propagated after the war by the people involved in the work to make and use the bomb as a way to make the process seem more deliberative than it was).