I read a book some time back called Rethinking the Principles of War. Basically its a collection of essays by experts on the subject of warfare and statecraft.
One of the first essays really made an impression on me, I think it was called 'An American Way of War?' The author examines about a dozen (cant remember exactly how many) aspects of American war making some positive some negative. Two that stick out in my mind are 1.) Logistically Excellent, and 2.) Culturally ignorant (or something similar).
It made an impression because in the essay the author makes the argument that when we decide to wage war we do so with great efficiency, superior logistical support, etc. Essentially we are really good at the fighting part, but we are absolutely terrible at fully understanding the social environment we are about to enter. Vietnam and our current experience in the Middle East I think are pretty good supporting examples.
Granted I haven't deployed to the area, so my experience is based solely off what I have read, but it seems to me we have had to learn the hard way that you cant just invade a country and expect things to just fall in place for you, even if you win every single firefight.