What the main enemies in Iraq are doing is just scorched earth. Make the place hell. If someone really wants to do that, how do you stop them? I think we were running a football "prevent defense" and that gives the terrorists too much running room to destabilize areas.
You go after their puppet masters - Iran.
That moves the war to Iran taking the terrorists focus off of Iraq. They can't afford to lose Iran so the front will move there.
"[They] Make the place hell. If someone really wants to do that, how do you stop them?" - by making it even worse hell, that's how.