Iraqis on the road to retaking Mosul.

Photographer: Mahmoud Al-Samarrai/AFP/Getty Images

Islamic State Has Good Reasons to Retreat in Iraq

Noah Feldman is a Bloomberg View columnist. He is a professor of constitutional and international law at Harvard University and was a clerk to U.S. Supreme Court Justice David Souter. His books include “Cool War: The Future of Global Competition” and “Divided by God: America’s Church-State Problem -- and What We Should Do About It.”
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There’s no need to believe the Russian propaganda that says the U.S. agreed to let 9,000 Islamic State fighters flee Mosul to go fight President Bashar al-Assad in Syria. But the story “reported” Wednesday by Russia Today (on the basis of a single anonymous source) does capture a strategic truth in the run-up to the attack on the Islamic State-controlled city: The fighters have good reason to flee -- and the Iraqis and the U.S. have good reason to let them.

The battle to retake Mosul has been a long time coming. Islamic State occupied the city in June 2014, without encountering much in the way of Iraqi military resistance. Mosul was the biggest and most important city to fall into the hands of the self-proclaimed caliphate. Before Islamic State arrived, it had a population of roughly 2 million, making it Iraq’s third most populous city. (Since then, at least half have fled or been expelled or killed, including essentially all the ethnic and religious minorities such as Kurds, Turkmen, Assyrian Christians and Yazidis.)

With Mosul, Islamic State controlled a significant portion of Iraq. The Baghdad government couldn’t allow that indefinitely without appearing to give up on functioning as a sovereign state.

Yet Baghdad took its time. First, it had to retake Ramadi, which didn’t fall until February. That required the use of Shiite militias backed by Iran, which Iraqi Prime Minister Haider al-Abadi ideally doesn’t want to repeat.

Abadi has been worried about the political cost of a failed assault by Iraqi regular troops. And the U.S., which will have to support the attack from the air and with advisers on the ground, hasn’t wanted to press the timing too hard. There’s little political advantage to be gained from a major conflict in Iraq during the election season. And there’s plenty to lose if the attack falters.

Nevertheless, the first deployments of Iraqi troops near Mosul began in the spring. A slow encirclement has been proceeding apace. And a full-on push is now assumed by all to be imminent.

That leads to the $64,000 question: To what extent will Islamic State stand and fight? No one doubts that there will be some resistance, and the Pentagon says the defense includes trenches and booby traps.

But as long ago as July, the Iraqi defense minister claimed militant leaders and fighters were leaving the city. This report probably had some truth to it. Recent reports from inside the city say that most non-Arab and foreign fighters have left.

The logic of tactical retreat is strong for Islamic State. Its ideological predecessors in the Iraqi Sunni insurgency stood and fought the U.S. in the second battle of Fallujah in 2004 -- and were resoundingly defeated, at significant cost in manpower. Perhaps 1,500 insurgents were killed, and another 1,500 captured.

The lesson for Islamic State is not to fight an unwinnable battle. Instead, the best strategy is to act like a classic insurgent force: offer only token resistance at the advance of regular troops, and return if and when the Iraqis seem like they can’t defend or control Mosul. It’s far from certain that the Iraqi state can effectively govern Mosul or control potential ethnic conflict.

There’s some cost for the caliphate in giving up territory, simply because its legitimacy has derived from controlling so much of it. But because Islamic State still controls plenty of territory in Syria, that’s a cost it can probably bear.

As for the Iraqis and the Americans, they’d like nothing better than to take Mosul without firing a shot, the way Islamic State did in 2014. No one is really sure how well the Iraqi army will operate under fire; its record isn’t very impressive. U.S. airstrikes will inevitably kill civilians and devastate the city’s infrastructure, which will make rebuilding harder, which in turn will make it harder for the Iraqi government to establish control.

Also, no one knows exactly how many fighters are in the city. One Kurdish estimate from September put the number at 20,000. That sounds high, but U.S. estimates of 3,000 to 4,500 may be optimistically low.

So if Islamic State fighters want to leave Mosul now, it’s in Iraqi and U.S. interests to let them go. Killing militants as they retreat toward the Syrian border might backfire by forcing Islamic State to stay and fight in Mosul.

This brings us back to the Russian fantasy that the fighters will be allowed to go to Syria to fight Assad -- and his Russian allies.

The U.S. and Iraq have, of course, no interest in seeing an Islamic State offensive against Assad. The Barack Obama administration is not going to ally itself with Islamic State, the ideological source of terror attacks on the home front and in Europe.

But there is a certain zero-sum effect to the movement of Islamic State troops. In practical terms, any fighters who are able to make it to Syria will in fact strengthen Islamic State against its opponents, including Assad.

In the long run, the answer for the U.S. is to reduce the caliphate’s geographic footprint. Retaking Mosul will be part of that process. But victory over Islamic State will ultimately require solving the question of Syria. And that remains a bridge too far for U.S. policy, even though Russian President Vladimir Putin has a very clear idea of the result he wants.

  1. The militias are in use around Mosul, but the government says they won’t participate in the main assault. Meanwhile, Turkey is saying it wants the Sunni militias it has trained to take part -- which Abadi is resisting.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

To contact the author of this story:
Noah Feldman at nfeldman7@bloomberg.net

To contact the editor responsible for this story:
Stacey Shick at sshick@bloomberg.net