Here's One Glaring Problem With A US-Iran Alliance In Iraq

Iran and the United States are reportedly discussing possible security cooperation in Iraq, where an extremist group has seized large portions of the country's north. Some members of Congress, including the usually-hawkish Lindsay Graham, seem to be on board with a greater level of U.S.-Iranian cooperation.

There is one glaring issue regarding that partnership.

If the plan comes to pass, Washington and Tehran would be working together to fight an organization whose presence Iran has tolerated on its own territory, and that it might have directly helped nurture - during a time when that group was responsible for killing thousands of Iraqis and American soldiers.

The Islamic State of Iraq and the Levant (ISIS), which seized the northern oil city of Mosul last week and is currently attempting to surround Baghdad, was once al-Qaeda's Iraq franchise - although disagreements over the group's ambitions and geographic reach led to a rupture between ISIS and al-Qaeda central last year. During the U.S.'s military presence in Iraq, AQI was the country's most brutal insurgency, a sectarian terrorist organization that plunged Iraq into civil war.

That war was partly between Shi'ite militants, some of which were supported by Iran, and AQI, an affiliate group of the world's leading Sunni terror organization.

And Iran was playing both sides of the conflict.

As a 2008 backgrounder from the Institute for the Study of War recounted, there were numerous incidents of U.S. military and intelligence officials alleging a connection between Iran and Sunni extremists in Iraq. In April of 2007, General William Caldwell alleged that "there has been some support provided to some Sunni extremist groups by Iranian intelligence agents, not anywhere near the degree that it's obviously being done to Shi'a extremists, but there are now some confirmations we've been able to make."

The next month, coalition forces captured "a suspected liaison to al-Qaeda in Iraq senior leaders, who assists in the movement of information and documents from al-Qaeda in Iraq leadership in Baghdad to al-Qaeda senior leaders in Iran," according to an official press release.

Also in 2007, journalist Eli Lake reported that the U.S. intelligence community had intercepted Iranian documents detailing cooperation between members of the Iranian Revolutionary Guard's Qods Force and members of Al Qaeda in Iraq.

These efforts have paid off, according to the State Department's current explanation for Iran's classification as a state sponsor of terrorism. According to State's 2013 overview,

Iran allowed AQ facilitators Muhsin al-Fadhli and Adel Radi Saqr al-Wahabi al-Harbi to operate a core facilitation pipeline through Iran, enabling AQ to move funds and fighters to South Asia and also to Syria. Al-Fadhli is a veteran AQ operative who has been active for years. Al-Fadhli began working with the Iran-based AQ facilitation network in 2009 and was later arrested by Iranian authorities. He was released in 2011 and assumed leadership of the Iran-based AQ facilitation network.

There are any number of reasons for an expansionist Shi'ite theocracy to support equally-expansionist Sunni extremists in the midst of a Sunni-Shi'ite civil war. As Lake explained, Iran viewed its ties to al-Qaeda as a hedge against potential blowback from the chaos in neighboring Iraq.

In the late 2000s, Tehran might also have thought that support for Sunni extremists might also have had the ancillary benefit of weakening the U.S. military or even hounding it out of the region. Iran would eventually play a major role in getting the U.S. to leave Iraq, but not through support for Sunni terrorists - instead, Iran used its active role in negotiations over Iraq's new government in 2010 to covertly secure the exit of U.S. troops from the country.

And there are higher-level strategic considerations at play. For the past year, there have been accusations that the Assad regime in Syria - an ally of Iran, whose leaders belong to the minority Alawite sect, which is associated with Shi'ism - is in a classic Baptists and bootleggers coalition with ISIS. They're enemies whose behavior nevertheless reinforces and benefits the other.

As one Western diplomat put in January in an interview with Time,

[T]here is regular contact between regime forces and al-Qaeda elements, but he is not sure that it amounts to outright collusion. "I have no doubt that there are links," he says. "But ISIS' indirect assistance to the regime through oil sales, and the regime's implicit acceptance of ISIS presence in some areas, may just be a tactical alliance that allows both entities to pursue the same short term goals."

And that's hardly the only evidence that Assad and ISIS are acting on an awareness of their mutual interests, as Business Insider's Michael Kelley recounted in January. Basically, Iran and its top Arab ally has tolerated the same Sunni extremist group that is now fighting Iranian-supported militias in Iraq.

The result has been a stronger Assad regime, in addition to an emerging sense that there is a confluence of U.S. and Iranian interests in Iraq.

The U.S. and Iran might end up entering into an uneasy alliance of necessity in Iraq. But the situation in the country is partly the result of Iran's success in playing both sides of the region's sectarian divide, in a way that benefits its allies, and has forced even the United States to constantly alter its strategy in the oil-rich heart of the Arab Middle East.