The U.S. relationship with war is evolving in a difficult to predict fashion. Most nations operate on the premise that the best way to win a war is not to get into it in the first place. However, war serves a useful purpose for the U.S.. It gives them a chance to test out the latest tech, make their contractors some money, reduce unemployment, and give the latest batch of west-point kids their manhood rights. The U.S. will likely keep getting involved in wars periodically no matter how flimsy the pretext for them is. What nature those wars will take is what is really interesting.
Obama's "we can kill anyone we want, anywhere we want, anytime we want" policy really does put an interesting spin on things. If extraterritorial strikes had been commonplace ten years ago the Afghanistan war might never have happened. Assuming bin Laden hadn't gone to ground by that point, they might simply have executed him without the Taliban state's permission, just as he was eventually killed without Pakistan's knowledge or permission. Avoiding a war might have been worth the dubious legality of such an action, but it would have let a truly nasty genie out of its bottle (one that the U.S. later released anyways without stopping a war!). What will happen when other nations inevitably follow the U.S.'s example? Also, it's one thing to execute terrorists in this manner, but could the U.S. eventually pursue "regime change" this way? How many pentagon generals are currently chomping at the bit to send drones out after Ali Khamenei?
In the end , the root of the problem really is that war is good for business and the U.S. political system is a thrall to business interests. Fix that and everything changes!