Posted previously about Saudi economic interests expanding in Iraq, perhaps they may provide balance needed in the area without dividing Iraq.  Also since wahabbis (al Qaida) originated in Saudi Arabia, then let them deal with the problem they failed to do so before. 

"Iran or a mini-bargain with the Saudis?

Even with all of the recent talk about foreign policy "realism," one of the major tenets of leading realists (George F. Kennan and Hans Morgenthau come to mind) has gone largely ignored. Most realists subscribe to the view that any state that seeks to accumulate too much power will almost surely provoke a balancing coalition of other states seeking to check the expansion of its influence.

Many realists would argue that the U.S. has experienced this phenomenon to its detriment in the past few years. Some realists would also maintain that if the U.S. is "checked" in Iraq, the same dynamic will come into play against the emerging power in the region -- Iran. Under this scenario a coalition, led most likely by Saudi Arabia, will seek to balance Iranian power. The religious divide between Sunni and Shia will help propel the coalition building.".............

http://powerlineblog.com/archives/016092.php

(excerpt)

Then again, what about Mr. Bush? Why hasn't he been able to bring order to Iraq with the United States military? Here's the answer: As a creature of Shi'ite thug-o-crats, Mr. Maliki's hands are tied. As creatures of political correctness, we have tied our own hands. And almost literally. The PC rules of engagement imposed on American soldiers have as much to do with the chaotic limbo our troops find themselves in as failed political policies. Closely held, these rules -- burdensome constraints, really -- have become obvious to everyone, including our foes. News reports tell us potential targets in Iraq must be engaged in hostile acts, or show "clear intent," before our men can take a shot at them. Mosques where insurgents seek shelter and store arms are no-go zones for American soldiers. We don't even shut down mosque loudspeakers that broadcast incitement against our troops. Marine Maj. Jeffrey O'Neill put it this way to the Christian Science Monitor: "Many would ask: What other war would we allow the enemy to broadcast calls for our defeat for the sake of cultural sensitivity?"
The answer is no other war, at least no other war fought to win. But we don't even know what victory looks like -- unless anyone seriously believes victory looks like just another basic death-to-America-and-Israel Shariah state dominated by Shi'ites with ties to jihadist Iran. Next to such a prospect, chaotic limbo doesn't look good, but it does postpone that sure-to-be nasty shock of recognition."........
......."Here's an "or else" scenario from Nawaf Obaid, an adviser to the Saudi government, that actually sounds promising -- not a term that usually springs to my mind to describe Saudi scenarios. Contemplating what he would call an unwelcome American withdrawal from Iraq, Mr. Obaid writes that the Saudi government just might fill the breach out of "religious responsibility" to Iraq's Sunni minority. Saudi Arabia, "the de facto leader of the world's Sunni community," Mr. Obaid writes, just might decide to support Iraq's Sunni fighters, just as Iran has been supporting Iraq's Shi'ite fighters, to avert a possible "full-blown ethnic cleansing."...................

http://www.washtimes.com/op-ed/20061130-084530-2852r.htm