As America washes its hands of responsibility in the Middle East it has effectively resuscitated Tehran’s dreams of regional power. Indeed, one of the primary complicating factors in Syria and Iraq has been that US reluctance to use its own troops on the ground has led to a reliance on Iranian forces and Iran-backed Shia militias. This common thread draws the two conflicts further together and has enabled Iran to extend its hegemony over Damascus, Baghdad, Beirut and Sanaa. US reluctance to act in Syria is largely out of concern that Shia militias in Iraq might retaliate. America urgently needs to reduce its reliance on Iranian forces. Obama’s personal mission to conclude nuclear negotiations with Tehran only reinforces the extent to which Tehran can limit American action. The humanitarian consequences of Iranian support are clear in Tikrit. Shia militias are preventing the return of displaced residents while systematically destroying the city. It is incomprehensible why America is pursuing the same strategy for retaking Ramadi, simply transferring territory from ISIS to Iranian control

America faces the dilemma in Syria either of pursuing the politically unthinkable U-turn of supporting Assad or arming rebels who may or may not prove to be moderate or militarily decisive. ISIS’s current success might have opened a slim window of possibility. Both Sunni Saudi Arabia and Shia Iran share an interest in defeating ISIS before it reaches their own borders. Their mutual balance of weakness would not enable a formal deal between them but might allow a ceasefire among their Syrian proxies in order to focus efforts on ISIS. A government of national unity might be brokered that balanced power between Sunni and Shia. Assad’s regime looks increasingly fragile. His Iranian and Russian sponsors are negotiating his exile with the West, in order to bolster their own strategic positions. Despite his apparent war crimes, Assad’s personal fate matters less than the stability of Syria.

The primary focus of the US should be on Iraq, regardless of whether a ceasefire is achievable in Syria or Iran is forced to deal with ISIS in Syria unilaterally. The only way to defeat ISIS is with a ground force that will clear and then secure and rebuild currently occupied territory. Clearing ISIS from areas it holds is necessary but insufficient to prevent their return. The areas have to be rebuilt, repopulated and secured. ISIS’s operations in Iraq and Syria can be divided by a physical force that enters at Kobane. From here it would make sense to exploit ISIS’s weakest physical links between Raqqa and northern Aleppo along the upper Euphrates. Not only will this physically destroy claims to a caliphate but a divided ISIS force will be easier to defeat operationally. Equally the US has to increase the tempo of its air operations. The current level is too limited to have a meaningful effect on a disciplined military force. Furthermore, a recent special forces conference in the US identified the areas of military deficiency in Iraq: a dearth of drones, a lack of intelligence on the enemy’s networks and counter-IED technologies, and no clear narrative to push back against the group’s messaging.

The most immediate way to deal with this is for Obama to lift the prohibition on American boots on the ground and start providing proper assistance to the Iraqis. Iraqi troops would benefit from combat advisers in the form of special forces, and forward air controllers would improve the accuracy of airstrikes. The US Joint Special Operations Command was remarkably efficient between 2003 and 2010 both in gathering and acting on intelligence. It was a significant factor in the successful campaign against al-Qaeda. There is every reason to believe it could achieve the same against high-level ISIS leadership even if it was simply providing the intelligence-gathering and analysis for Iraqi special forces to act upon.

Current estimates of effective force sizes range from 10,000 (according to former head of Central Command General Anthony Zinni) to 25,000 (according to military analyst Fred Kagan). These are relatively modest numbers, compared to the peak of 176,000 coalition forces during the second Iraq War. However, the US is not a suitable unilateral force both because of domestic opposition and also due to the need for regional political legitimacy, which America does not carry by itself. A multinational force would need to consist of the US in partnership with Arab and Western states.