Iraq more and more appears to be a three-ring circus, where it is hard to separate out the clowns from the lion-tamer. You got the Kurds, Sunnis and Shiites. Baghdad politics is for the clowns. For Washington, the suffering Yazidis are a side-bar. The hundred of thousands of Iraqis that died because of the invasion and occupation have been forgotten by the United States of Amnesia.
The main concern of Washington looks to be that the rebellious Sunnis not only captured U.S. advanced weapons from the Iraqi military but are now able to operate them. I would not be surprised that Obama has suddenly decide to be involved because the rebellious Sunnis now have the weapon to threaten the other players in the Iraqi circus.
The dismemberment of Iraq has been ongoing for many years. Now Washington fears that it is no longer the most important player in the drama.