Daniel Byman and Kenneth Pollock of the Brookings Institution have authored a cheerfully titled report, THINGS FALL APART: CONTAINING THE SPILLOVER FROM AN IRAQI CIVIL WAR. In it they argue that America has no choice but to prepare to contain an all out civil war in war in Iraq. Unfortunately, their own assessment, based on a study of civil wars over the last 30 years, notes,
The historical record of states that attempted to minimize or contain spillover from all-out civil wars is poor. Nearly all of them failed to do so. Those that "succeeded" often paid such a high cost as to render their victories pyrrhic. In many cases, states failed so miserably to prevent spillover that they were eventually forced to mount massive invasions to attempt to end the civil war instead.
What will it take to successfully contain a civil conflict within the borders of Iraq?
Successful efforts to end civil wars generally required a peace agreement to bring the war to closure and then an international security intervention with a personnel-to-population ratio of 20 per thousand (or higher) to keep the peace, combined with a major injection of international resources. In Iraq (excluding Kurdistan), such a security deployment could equate to a deployment of roughly
450,000 troops.
The President seems to be fresh out of the international goodwill to drum up 4,500 troops for Iraq, let alone 450,000! America does not currently have the ability or political will to place these types of numbers into Iraq. The Brookings plan is a bitter pill that neither the administration, nor the American public will want to stomach. Of course, the threat of a US - Iran conflict sparked by Israeli or US "Pre-emptive" strikes against Iran seems more threatening to me, than an expanded civil conflict in Iraq.