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Policy Analysis

PolicyWatch 2735

The Battle for Mosul and Iran's Regional Reach

Michael Eisenstadt and Michael Knights

Also available in العربية

December 5, 2016

Absent preventive measures, the Mosul campaign could increase Tehran's regional influence and embolden its proxies to act against U.S. forces in Iraq.

Iran was the primary foreign beneficiary of America's overthrow of the Taliban in 2001 and Saddam Hussein's regime in 2003, which were Tehran's foremost regional adversaries at the time. Likewise, if the United States does not take adequate preventive measures, Iran will be the primary beneficiary when Islamic State (IS) forces are destroyed and the so-called caliphate is dismantled in Iraq. Indeed, President-elect Trump voiced such fears during the final presidential debate in October, asserting that Tehran would be "the big winner" when the coalition retakes Mosul. Avoiding this outcome will require a combination of robust steps to keep the anti-IS coalition together, bolster Iraqi counterinsurgency capabilities, safeguard Baghdad's sovereignty, and deter Iran well after the battle for Mosul ends.


Saddam's ouster created a historic opportunity for Tehran to transform its foremost regional opponent into a client state and member of its so-called "axis of resistance." Consecutive Iraqi governments have resisted these pressures to a certain degree, seeking to cultivate the United States as a partner and a counter to Iranian influence. Yet Tehran has worked to diminish the perceived threat posed by the presence of American forces and a U.S.-backed government in Iraq -- a threat it fears may increase following the Islamic State's defeat and the swearing in of the Trump administration. It has also strived to ensure the primacy of the Iraqi Shiite community, minimize the influence of Sunni Arab states, and become the most influential outside power in Iraq.

Iran's subtle and cost-effective modus operandi in Iraq has served it well. Tehran does not push on closed doors, and rarely asks Iraqi leaders to act against Iraqi interests. Instead, it works with the grain as often as possible, helping the Iraqis achieve their objectives where they broadly coincide with its own. For example, while Iran's Islamic Revolutionary Guard Corps (IRGC) oversees policy in Iraq and has many commercial interests there, particularly in religious tourism, Tehran does not have ambitious economic goals in Iraq. Likewise, Iran would benefit if Iraq's Popular Mobilization Units (PMUs) developed into an IRGC-like parallel military organization that counterbalances and overshadows the Iraqi military -- a possible outcome if these mainly Shiite militias parlay battlefield achievements in Mosul into victories in the coming provincial (2017) and parliamentary (2018) elections. Yet this scenario is not a driver of Iranian policy. In this sense, Tehran's approach to Iraq is highly pragmatic -- as long as its interests are served, it will work with (and, if need be, abandon) any particular faction there.

One area to watch following the battle for Mosul are the so-called "redlines" that Iranian allies such as Hadi al-Ameri regularly communicated to the United States in the past. One such line was U.S. involvement in combat operations inside Iraq, but it was seemingly crossed when the United States launched Special Forces raids and artillery fire missions from Iraqi territory. Another redline was the establishment of bases solely for U.S. forces, but it too has been substantively crossed in locations such as Kara Soar Base (previously Firebase Bell). Iran has not responded to these developments so far, but this apparent restraint may have more to do with Tehran's desire to help the Iraqi government fulfill its urgent needs and stated policies.

Moreover, while Iran's decisionmaking on Iraq has traditionally been driven by internal developments there, this calculus could change after Mosul's liberation. For example, military tensions with the United States in the Persian Gulf, or a U.S. decision to ramp up support for the Saudi-led campaign against the Houthis in Yemen, could cause Iran to push back in Iraq, perhaps by waging a proxy campaign to hasten a post-Mosul U.S. drawdown.


Given that the coalition campaign against IS will likely drive much of the group underground rather than out of Iraq, a victory in Mosul will create opportunities for Iran. Many key IS figures are former Baath regime military officers, and they will go to ground and live to fight another day as previous generations of Baathist officers did after the 1963 pro-Nasserist coup, the 2003 U.S. invasion, and the 2007 U.S. surge. IS functioned well as an underground terrorist network in 2011-2014, and Baghdad lacks the capabilities to deal with this threat. Unless there is a fundamental change in the nature of Iraqi politics, the battle for Mosul and its potentially messy aftermath may simply pave the way for the next Sunni insurgency -- whether in the form of "IS 2.0," a reborn al-Qaeda in Iraq (AQI), a revived neo-Baathist organization like Jaish Rijal al-Tariqa al-Naqshbandia (JRTN), or something else. This scenario is especially likely if IS remains ensconced in Syria and uses its presence there to stage operations in Iraq.

Such an outcome would ensure Baghdad's continued need for a capable security assistance partner/provider, whether Washington or Tehran. The United States has a keen interest in being that partner of choice, but Iran's proximity and lingering questions about American reliability mean that Iraq will probably keep hedging its bets with Tehran. Meanwhile, local Iranian proxies will continue to engage in the sectarian cleansing of "liberated" areas in order to secure critical lines of communication and safeguard isolated or beleaguered Shiite communities.

In addition, Iran will likely try to establish an overland route through Iraq to Syria in order to supplement its air corridor to Damascus, which it uses to resupply Hezbollah and the Assad regime while projecting influence in the Levant. Tehran generally seeks redundant lines of communication to provide resiliency to its network of proxies and partners. While the air corridor would remain the most convenient connection and the primary means of ferrying troops there, a land corridor would enable it to send less urgently needed supplies by the less expensive land route. It would also broaden Iran's options if the United States ever took the unlikely step of establishing a no-fly zone over Syria, or if Israel were to close Damascus airport during a future war with Hezbollah. Perhaps more important, a land corridor would enable Iran to broaden its contacts with local populations, creating opportunities to exert influence and shape developments across the breadth of the Levant. Indeed, there are signs that the Iranian-supported PMUs who recently captured Tal Afar air base from IS are now converting it into a staging area for projecting influence in northern Iraq and Syria, once Mosul falls and additional Iraqi Shiite militiamen become available.


U.S. actions will be one of the most important shapers of Iranian behavior in post-Mosul Iraq. The more Washington steps back, the more Tehran will step forward. A repeat of the rapid coalition drawdown and disengagement seen in 2009-2011 would likely encourage Tehran to become more assertive in Iraq and better position it to counter U.S. activities there. Moreover, the Iraqi government is another key determinant of Iranian policies in Iraq, so the stronger Washington's relationship with Baghdad is, the better protected local U.S. equities will be.

For these reasons, the United States should consider five steps to counter Iranian influence in Iraq and prevent the return of IS:

1. Lock in the international coalition's commitment to Baghdad by enlisting its help on the following: securing Iraq's borders (especially with Syria), dealing with the heightened terrorism that is almost certain to emerge once the Islamic State is defeated as a quasi-conventional military force, and creating the basis for a multinational security venture that will outlast the war against IS. This means maintaining Combined Joint Task Force-Operation Inherent Resolve (CJTF-OIR) as a broad multinational coalition rather than allowing it to shrink back into a U.S. mission with a few token partners. In addition, Washington should approve a new three-year Iraq Train and Equip Fund II package for the Iraqi security forces to cover 2017-2020, supplanting the current ITEF covering 2014-2017.

2. Rethink the CJTF's approach to security force assistance, building on the training successes of the past year to establish create a more effective Iraqi counterinsurgency force. Rather than trying to create a miniature Western military force, the United States and its partners should consider new options that account for local cultural realities, avoiding incentive structures that breed corruption and prevent Iraqi forces from preparing properly for combat and stabilization operations. Beyond the emergence of more inclusive politics in Baghdad, this would be the best way to stave off the return of IS and the growth of Iranian influence via the PMUs.

3. Help Baghdad resist pressure to institutionalize the pro-Iranian PMUs as a large, well-funded parallel military force that could rival the Iraqi security forces. The best way to accomplish this is to win the Mosul battle without heavy reliance on the PMUs, then maintain a robust and effective multinational security force assistance effort thereafter. Looking out for the many Counter-Terrorism Service officers in the senior ranks of the Iraqi military is also important. Washington will have no greater long-term partners than these U.S.-trained officers, so they need to be listened to, protected against militia intimidation, and supported in their careers.

4. Deter Tehran by quietly indicating that the United States will not tolerate Iranian proxy attacks on its personnel in Iraq. This includes making clear that any such incidents will have adverse consequences for Iran's own advisors in the region, as well as for IRGC naval vessels shadowing U.S. ships in the Gulf. To bolster the credibility of these warnings, Washington should continue to push back against the destabilizing activities of Iranian partners elsewhere in the region, such as the Houthi forces who have sought to disrupt freedom of navigation in the Bab al-Mandab Strait.

5. Prepare an inform-and-influence campaign documenting malign Iranian activities in Iraq, including unfair business practices, undue influence in politics, and sponsorship of violence against Iraqis. Such a campaign might provide leverage against Tehran, especially if the information were used as a warning shot and released via media outlets that do not traditionally lean Washington's way. Iran has never been very popular in Iraq, even among Shiites (though the fight against IS has dampened such resentments). Iraqis might therefore be interested to learn how expensive Iranian military support and gas/electricity imports really are; how coercion and violence make up the unseemly underside of the Iranian-dominated Shiite religious tourism industry; and how customs-free food imports from Iran have an adverse impact on Iraqi farmers. Finally, the defeat of IS in Iraq might reduce domestic support for Iran's costly presence in Syria, creating conditions conducive to an influence campaign in Iran that highlights these costs and politically complicates Tehran's ability to project power in the region.

Michael Eisenstadt is the Kahn Fellow and director of the Military and Security Studies Program at The Washington Institute. Michael Knights, the Institute's Lafer Fellow, recently returned from a trip to Iraq.