Guerrilla operations require local support. Liquidate the local Sunni Arab population, and that support goes away. This was how Saddam dealt with Shiite and Kurdish revolts. The Kurds and the Shiites will probably do something similar with the Sunni Arabs if GI's don't get involved on the ground.
Maliki was accused of being too sectarian. He wasn't really all that. Sure, he handed all the goodies to Shiites. But he really did not do much apart from turning a blind eye to very occasional Shiite militia attacks on Sunni Arabs. In contrast, Saddam killed an estimated million people to forestall plots against him. If some other country wants to play armed social worker, that's certainly its prerogative. I think we've wasted lost too many good Republicans and Christians in Iraq. It's time to let the natives do what they have to do. If Iraq's and Syria's Sunni Arabs have to find a new home in the gulf region, so be it.
We've wasted loads of money supporting islamic nutjobs (now it's the Kurds) and leaving Christians to perish in the Middle east. We can't be seen helping Christians because that would be racist or intolerant or whatever. So we support their enemies in the Middle East and we bombed them in Serbia. Does this make sense?