I don't have a lot of time right now, so will confine myself to saying that a quick perusal of Pres. Obama's National Defense University speech reveals some important statements that he should have made in this way some time ago -- but mieux vaux tard que jamais.
Especially important, I think, is the paragraph where Obama says (I'm not quoting here, but giving the gist) that he will work to create the conditions in which the AUMF (the Congressional 2001 authorization of military force against those who planned and carried out the 9/11 attacks or harbored them) can eventually be repealed -- because it will no longer be needed. The speech is a firm rebuke to the misguided notion of endless war, a notion that was reinforced by G.W. Bush's pronouncement that 9/11 required the U.S. to be at war with "all terrorist groups of global reach," whether they had had anything to do with 9/11 or not.
Obama's NDU speech is really the antithesis of the Bush Doctrine, which was an overweening, foolish, Manichaean conception of an endless global struggle between the forces of good and the forces of evil. It was a simplistic, ahistorical quasi-fantasy: foreign policy for people who think the world is a (bad) movie. One may not agree with all aspects of the NDU speech, but at least you can tell that most of it was written by grown-ups.