America no longer knows how to fight a war
When educated Americans think about war, they’re apt to think of it in ideological terms. Wars are fought between dictatorships and democracies and the goal is to establish one form of government or the other in the defeated opponent’s territory. That’s certainly been the way American policymakers have thought about the wars of this century and it was the framework during the Cold War as well, when the conflict was said to be, fundamentally, a clash of ideologies. The French Revolution is probably the source of this concept, as the wars it set off were indeed largely about regime change, if not that alone.