How can the Shiites and Sunnis be controlled? Invading Iran of course! It helped Caesar keep his enemies divided and allies beholden when he invaded Britain (although he didn't plan on staying for long.). Invading Persia kept conquered Greece united in a new and impressive way for Alexander and he became Magnus as a bonus. It's the next logical step for our criminally imperious leadership to take and it's so bloody tempting too. They need to restart the overt shooting war and quick if they wish to maintain any sort of initiative over the situation in Iraq. If they can drop bombs on anyone they please they will control the headlines again. They can have the bobble head major generals fan out over the airwaves and say how great everything is.
If Iran were invaded the Sunnis Arabs in Iraq would probably volunteer to help the GIs! Insuregency solved. Then Saddam's old boys can get their jobs back cowing the shiite Arabs. The Shiite would be put back in their place and Iran would be a charnel house.