(The post originally appeared on the author's website, Stratfor.)

The status of Iraq has always framed the strategic challenge of Iran. Until 2003, regional stability — such as it was — was based on the Iran-Iraq balance of power. The United States invaded Iraq on the assumption that it could quickly defeat and dismantle the Iraqi government and armed forces and replace them with a cohesive and effective pro-American government and armed forces, thereby restoring the balance of power. When that expectation proved faulty, the United States was forced into two missions. The first was stabilizing Iraq. The second was providing the force for countering Iran.

The United States and Iran both wanted to destroy Saddam Hussein’s Baathist regime, and they collaborated to some extent during the invasion. But from there, their goals diverged. The Iranians hoped to establish a Shiite regime in Baghdad that would be under Tehran’s influence. The United States wanted to establish a regime that would block the Iranians.

The U.S. Challenge In Iraq

In retrospect, U.S. strategy in Iraq was incoherent at base. On one hand, the American debaathification program drove the Sunni community into opposition and insurgency. Convinced that they faced catastrophe from the Americans on the one side and the pro-Iranian government forming in Baghdad on the other, the Iraqi Sunni Baathists united in resistance with foreign jihadists. At the same time the Americans were signaling hostility toward the Sunnis, they also moved to prevent the formation of a pro-Iranian government. This created a war between three factions (the Americans, the Shia and the Sunnis) that plunged Iraq into chaos, shattered the balance of power with Iran and made the United States the only counterweight to the Iranians.

All of this turned what was intended to be a short-term operation into an extended war from which the United States could not extract itself. The United States could not leave because it had created a situation in which the Iranian military was the most powerful force in the Persian Gulf region. Absent the United States, the Iranians would dominate Iraq. They would not actually have to invade (Iran’s military has a limited ability to project force far from its borders in any case) to extract massive political and economic concessions from both Iraq and the Arabian Peninsula.

An unchecked Iran, quite apart from its not-yet-extant nuclear capability, represents a profound strategic threat to the balance of power in the Persian Gulf. Assuming the nuclear issue was settled tomorrow either diplomatically or through attacks, the strategic problem would remain unchanged, as the central problem is conventional, not nuclear.

The United States is set to complete the withdrawal of its combat forces from Iraq this summer, leaving behind a residual force of about 50,000 support personnel. This drawdown is according to a plan former U.S. President George W. Bush laid down in 2008, and that U.S. President Barack Obama has sped up only by a few months. Therefore, this is not a political issue but one on which there has been consensus. The reason for the withdrawal is that U.S. forces are needed in Afghanistan. Even more important, the United States has no strategic reserve for its ground forces. It has fought a two-theater, multidivisional war for seven years. The Army is stretched to the limit, and should another crisis develop elsewhere in the world, the United States would lack the land power to respond decisively.

Avoiding this potential situation requires drawing down U.S. forces from Iraq. But simply abandoning the Persian Gulf to Iranian military and political power also represents a dangerous situation for the Americans. Therefore, the United States must balance two unacceptable realities.

The only hope the United States has of attaining this balance would be to achieve some semblance of its expectations of 2003. This would mean creating a cohesive Iraqi government with sufficient military and security capabilities to enforce its will internally and to deter an attack by an Iranian force. At the very least, the Iraqis would have to be able to hold off an Iranian attack long enough to allow the United States to rush forces back into Iraq and to suppress insurgent elements from all Iraqi communities, both Sunni and Shiite. If Iraq could do the former, the Iranians likely would refrain from an attack. Iranian rhetoric may be extreme, but the Iranians are risk-averse in their actions. If Iraq could do the latter, then they eliminate Iran’s preferred mode of operations, which is covert subversion through proxies.

The issue therefore boils down to how the United States answers this question: Can the Iraqis form a coherent government in Baghdad capable of making decisions and a force capable of achieving the goals laid out above? Both the government and the force have to exist; if either one is lacking, the other is meaningless. But alongside this question are others. Does Iraq have any strategic consensus whatsoever? If so, does it parallel American strategic interests? Assuming the Iraqis create a government and build a significant force, will they act as the Americans want them to?

State vs. Faction

The United States is a country that believes in training. It has devoted enormous efforts to building an Iraqi military and police force able to control Iraq. The Americans have tried to imbue Iraq’s security forces with “professionalism,” which in the U.S. context means a force fully capable of carrying out its mission and prepared to do so if its civilian masters issue the orders. As professionals, they are the technicians of warfare and policing.

But perhaps the fundamental question of any military force, one that comes before training, is loyalty. In some militaries, the primary loyalty is to oneself. In such militaries, one joins to make a living, steal what one can and simply survive. In other militaries, the primary loyalty is not to the state, but some faction of the country, be it religious, ethnic or geographical. No one is going to give his life defending a state to which he is indifferent or even hostile, no matter how carefully trained in handling his weapon or how well-lectured he is on the question of professional responsibility. Neither of these conditions allows for a successful military in the end. A man in it for himself is not going to go into harm’s way if he can help it. A man in the military to protect his clan is not going to die to protect those to whom he has no loyalty.

The U.S. Army has trained tens of thousands of Iraqis. And Americans are great trainers. But the problem isn’t training, it is loyalty. Professionalism doesn’t imbue anyone with self-sacrifice to something alien to him.

And this is the challenge the United States faces in the Iraqi government, which like most governments, consists of many factions with diverging interests. In viable states, however, fundamental values shared by the overwhelming majority lie beneath the competing interests, be they a myth of country or of the moral principles of a constitution. It is simply not apparent that Iraqi factions have a core understanding of what Iraq should be, however, nor is it clear whether they owe their primary loyalty to the state or to some faction of Iraq.

Saddam Hussein held the state together by a complex of benefits and terror. He became the center of Iraq, and in a sense became Iraq. Once he was destroyed, Iraq’s factions went to war with each other and with the United States, pursuing goals inimical to a united Iraq. Therefore Iraq’s reconstituted military and security forces, however intermixed or homogenized they may be, still owe their individual loyalties to their factions, which will call on them to serve their people, a subset of Iraq.

The United States plans to withdraw its combat forces by the summer. Leaving aside how well-protected the remaining 50,000 noncombat troops will be, the question persists on who will hold the country together. The Iranians certainly are not eager to see the Iraqi situation resolved in favor of a government that can block Iran’s ambitions. The Iranians have longstanding relations with any number of Iraqi Shiite groups, and even with some Kurdish and Sunni groups. Iran would have every reason to do what it can to destabilize Iraq above and beyond any indigenous destabilization of Iraq in order to help shape a government it can dominate. In our view, Tehran has the tools to do this effectively.

The American leadership is certainly aware of this. It may hope or even believe that a stable Iraqi government will emerge, and it will certainly not say anything publicly that would decrease confidence in the process. But at the same time, the American leadership must privately know that the probability of a cohesive Iraqi government commanding a capable and loyal security force is far from a slam dunk.

In Search of a Plan B

Therefore, logic tells us that the United States must have a Plan B. This could be a plan to halt withdrawals. The problem with that plan is that there is no assurance that in three months or a year the core divisions of Iraq could be solved. The United States could be left without forces for a strategic reserve without any guarantee that time would solve the problem. A strategy of delay calls for some clear idea of what delay would bring.

Or the United States could complete the withdrawal on the assumption that the Iranians would not dare attack Iraq directly while the residual U.S. force remained. The problem with this strategy is that it is built on an assumption. This assumption is not unreasonable, but it is still an assumption, not a certainty. Moreover, Iran could covertly destabilize Iraq, putting U.S. forces without sufficient combat capability in harm’s way from Iranian-supplied forces. Finally, Iran’s major audience consists of the oil powers of the Arabian Peninsula. Tehran wants to show the Gulf Arabs that the United States will withdraw from Iraq regardless of potential consequences to them, reducing their confidence in the United States and forcing them to contemplate an accommodation with Iran.

Halting the withdrawal therefore poses substantial challenges, and completing the withdrawal poses even more. This is particularly the case if the United States completes the withdrawal without reaching some accommodation with Iran. But negotiating with the Iranians from a position of weakness is not an attractive option. The Iranians’ price would be higher than the United States wants to pay. Therefore, the United States would have to make some show of power to the Iranians that will convince the Iranians that they are at risk. Bombing Iran’s nuclear facilities could fit the bill, but it has two drawbacks. First, the attacks might fail. Second, even if they succeeded, they would not have addressed the conventional problem.

Washington’s way forward depends upon what the American government believes the probabilities are at this point for a viable Iraqi government and security force able to suppress insurgencies, including those fomented by Iran. If the Americans believe a viable Iraqi government is a possibility, they should roll the dice and withdraw. But it is not clear from our point of view what Washington is seeing. If it believes the probability is low, the United States not only will have to halt the withdrawal, it will have to reverse it to convince the Iranians that the Americans are hypercommitted to Iraq. This might cause Tehran to recalculate, opening the door for discussion.

It is now April, meaning we are four months from the deadline for the completion of the withdrawal of U.S. combat forces from Iraq. In the balance is not only Iraq, but also the Iranian situation. What happens next all comes down to whether the mass of parties in Baghdad share a common foundation on which to build a nation — and whether the police and military would be loyal enough to this government to die for it. If not, then the entire edifice of U.S. policy in the region — going back to the surge — is not merely at risk, but untenable. If it is untenable, then the United States must craft a new strategy in the region, redefining relationships radically — beginning with Iran.

As with many things in life, it is not a matter of what the United States might want, or what it might think to be fair. Power is like money — you either have it or you don’t. And if you don’t, you can’t afford to indulge your appetites. If things in Baghdad work themselves out, all of this is moot. If things don’t work out, the Obama administration will be forced to make its first truly difficult foreign policy decisions.