"the pilots, presumably, would not bomb the civilian populations of nations with whom there is no war."

When was the last time the USA declared war before sending in the bombers? Or just about anyone else for that matter.

And it's not just a matter of there now being a convention now that wars are started without any declaration - now it appears a faitly routine procedure to carry out air-raids at a time when there is no suggestion that a state of war exists between the bombers and the targetted nation. For example in Iraq, Sudan, Libya.