Well, the whole reason behind rebuilding the country you attacked has to do with all the no-bid contracts and possibly strenghtening your hold over a country. Or in other words, occupation.
In my opinion, as usual, I've noticed that it seems that in the 21st century, instead of physical troops occupying countries, they only beat them into submission, so central banks and mercenary groups can come in. (For instance, in Libya, first things the rebels set up were oil lines to sell to the West, as well as central banks to take monetary control over the country). Much more efficient than physical force. They'll just very slowly tax those people into submission.
With, apparently, over 700 U.S bases over the world, who's to say what precedent this way of taking over, sets?
http://www.bbc.co.uk/news/business-12969004http://www.cnbc.com/id/42245997(Just a few sources on above's stuff)