You don't want to fall into the trap of thinking new wars are new at all. I'm sure it has already been mentioned. Yes the end of the Cold War left the sole great power of the world reflecting on its new role in the world. There is plenty of stuff out there on how the 90's were punctuated by the humanitarian intervention and how at the end of the decade there was a massive over reliance on airpower. In terms of the US military machine (or the military machine of any nation) they are only as good as the last war they fought. That is to say, and I know it is somewhat cliche, but armed forces seems to go into any new conflict and conduct it the same way they conducted the last conflict they were involved in. See the massive use of airpower in Afghanistan in 2001 or in Iraq in 2003 and compare it to the use of airpower in Kosovo in 99'. I think militaries are very unwilling to admit they are doing something wrong almost as much as they are to admit defeat.