“IT is not going too far to say that American foreign policy has become completely subservient to tactical domestic political considerations.” Vali Nasr quoted by Roger Cohen in the New York Times
I think that Roger Cohen and Vali Nasr miss the point. Obama belongs to a mixture of Stephen Walt realism cum Chalmers Johnson "imperial winding down" school of America's role in the world. The idea behind this is that America is not to be the world's policeman, but rather spend its treasure on bettering the lives of its own population.
Taking office, he found himself saddled with two significant Clinton era, "liberal interventionists", Hillary and Holbrooke, who he had to disconnect, which he did.