Some have argued that this would therefore limit the U.S. involvement in "internal" Iraqi matters and allow the United States to remain neutral in the civil war. However, many of the jihadist groups with an anti-U.S. agenda are intimately tied to various Sunni factions in the civil war: the United States cannot go after the jihadists without being perceived as taking sides in the civil war. Moreover, even this more "limited" focus would not remove the U.S. military presence from the region. If such strike forces were launched from bases in Iraq's neighbors, they would upset the local population and likely face limits on their ability to operate in Iraq by the host governments. This was exactly the set of problems the United States encountered during the 1990s, which led Washington to eliminate some of its military facilities in the region after the invasion of Iraq.

On the other hand, if the United States were to leave a (smaller) residual military presence in Iraq only to try to hold down the terrorism problem without the political entanglements created by mounting strikes from Iraq's neighbors, this too will have negative repercussions for the terrorism threat. It will allow the salafi jihadists to continue to use this as a recruiting tool, although the diminished presence of U.S. troops will make this slightly harder. It will also mean that American troops will continue to be targets of terrorist attacks, although redeploying them from Iraq's urban areas to the periphery would diminish the threat from current levels. Thus, if such bases were retained only to deal with the terrorism problem they could incur many of the costs of the catch basins approach for much less of its potential benefit.

Finally, the United States will have to recognize the military limits of what can be accomplished. Terrorism in Iraq has flourished despite the presence of 140,000 U.S. troops: It is absurd to expect that fewer troops could accomplish more. The hope is to reduce the frequency of attacks and the scale of the training and other activities, but our expectations must, by necessity, be modest.

And we need to prepare for things going wrong. One would be the possibility of a disruption in the oil supply. Since 9/11, Sunni jihadists have shown a growing interest in attacking the world's oil infrastructure and have attempted several strikes on it, including in Saudi Arabia. Iraq is already victim to almost daily attacks on its oil infrastructure. If Iraq becomes even more of a haven for Sunni jihadi terrorists, it is likely that they will plot against the regional oil infrastructure and conduct additional attacks on parts of the Iraqi oil infrastructure outside their control.

The economic impact of such attacks could be considerable. A further reduction in Iraqi oil production would drive prices higher, given how tight world oil markets already are today. Of far greater concern, however, is the risk of attacks on Saudi Arabian production and transit facilities. Disruptions in the Saudi supply could send prices soaring. Even the greater risk of attacks would lead to an increased instability premium on oil, further increasing its price.

We will not be able to say that we have not been warned. This is one area where what we do outside of Iraq-building up the Strategic Petroleum Reserve in order to reduce the impact of price spikes on U.S. consumers, developing contingency plans under the aegis of the International Energy Agency so that leading oil-consuming countries can better manage the risk of disruptions-can enhance our freedom of action (and perhaps in turn reduce incentives to attack oil-production and transit facilities).

A Kurdish decision to secede from Iraq could provoke another crisis, especially if (as seems likely) Turkey, Iran and Syria move to oppose this. Because of the ease with which secessionism can spread, the number of groups in the Persian Gulf that could easily fall prey to such thinking and the determination of Iraq's neighbors to prevent this, it will be necessary for the United States to persuade the Iraqi Kurds not to declare their independence anytime soon. Iraq's Kurds (and all of the Kurds of the region) deserve independence, but this should only come as part of a legal process under conditions of peace and stability. In practice, however, Kurdistan must be managed as if it were independent-as if it were one of Iraq's neighbors. The Kurds are likely to share the same problems as Iraq's neighbors in terms of refugees flowing their way, terrorist groups striking out against them (and using their territory to conduct strikes) and the radicalization of their population.

The Kurds should be asked to police their own borders to minimize other spillover problems. In particular, the United States should press Iraq's Kurds to cooperate with Turkey to stop the militant Kurdistan Workers Party from using Iraqi Kurdistan as a rear base for its operations. Consequently, the United States will have to help the Kurds deal with their own problems of spillover from the civil war in the rest of the country and convince the Kurds not to "intervene" in the rest of Iraq. That will mean helping them deal with their refugee problems, giving them considerable economic assistance to minimize the radicalization of their own population and likely providing them with security guarantees to deter either Iran or Turkey from attacking them. One U.S. red line for Iran ought to be no attacks, covert or overt, on the Kurds.

Indeed, preventing Iran from intervening, especially given how much it has already intruded on Iraqi affairs, could be the biggest headache of all. Given Iran's immense interests in Iraq, some level of intervention is inevitable. For Tehran (and probably for Damascus too), the United States and its allies will likely have to lay down "red lines" regarding what is absolutely impermissible. This is especially the case should the United States choose to employ catch basins because of the logistical and political impossibility of creating them along the Iranian border-therefore requiring Washington to limit Iranian intervention in other ways. The most obvious red lines would include sending uniformed Iranian military units into Iraq, laying claim to Iraqi territory, pumping Iraqi oil or inciting Iraqi groups to secede from the country.

The United States and its allies will also have to lay out what they will do to Iran if it crosses any of those red lines. Economic sanctions would be one possible reaction, but this is only likely to be effective if the United States has the full cooperation of the EU-if not Russia, China, Japan and India as well. On its own, the United States could employ punitive military operations, either to make Iran pay an unacceptable price for one-time infractions (and so try to deter them from additional breaches) or to convince them to halt an ongoing violation of one or more red lines. Certainly the United States has the military power to inflict tremendous damage on Iran for short or long periods of time; however, the Iranians probably will keep their intervention covert to avoid providing Washington with a clear provocation. In addition, all of this will take place in the context of either a resolution of or ongoing crisis over Iran's nuclear program, either of which could add enormous complications to America's willingness to use force against Iran to deter or punish it for intervening in Iraq.

An Uncertain Endgame

THE RECOMMENDATIONS above-and others we laid out in a larger, earlier study-are not a panacea.⁴ If the surge fails and Iraq descends into all-out civil war, the United States will have to choose between bad options and worse ones. Moreover, these measures are simply designed to contain a civil war in Iraq, not shut it down. There is no endgame inherent in these options. Instead, the United States will have to weave a web around Iraq and hold it in place to contain the worst of the spillover at an acceptable cost while waiting for the conflict to burn itself out enough to make less costly solutions (potentially including some form of partition) possible.

How we got to this point in Iraq is an issue for historians (and perhaps for voters in 2008); what matters now is how we move forward and prepare for the enormous risks an Iraqi civil war poses for this critical region. As we prepare, we must remember that Iraq's descent into the abyss does not relieve us of our responsibilities: Dealing with the problems of spillover is likely to be costly, painful and bloody. But ignoring the risks could be even more dangerous.

Daniel Byman is the Director of the Center for Peace and Security Studies at Georgetown University's School of Foreign Service and a non-resident senior fellow at the Saban Center for Middle East Policy at the Brookings Institution. Kenneth Pollack is the Director of Research of the Saban Center for Middle East Policy at the Brookings Institution.

¹ Clay Wilson, "Improved Explosive Devices (IED) Technology in Iraq and Afghanistan: Effects and Countermeasures", Congressional Research Service, September 25, 2006, pp. 2.
² As quoted in Hassan M. Fattah, "An Island Kingdom Feels the Ripples from Iraq and Iran", The New York Times, April 16, 2006.
³ Sarah Lischer, "Collateral Damage: Humanitarian Assistance as a Cause of Conflict", International Security, 28, No. 1 (Summer 2003), pp. 79-109.
⁴ Daniel L. Byman and Kenneth M. Pollack, "Things Fall Apart: Containing the Spillover from an Iraqi Civil War", The Saban Center for Middle East Policy at the Brookings Institution, January 2007.

Essay Types: Essay