Four days after Iraqi government forces and allied Kurdish troops began advancing on the city of Mosul, Islamic State militants launched a surprising counterattack about 150 km away. Dozens of fighters besieged the oil-rich city of Kirkuk before dawn on Oct. 21, setting off gunbattles, suicide bombings and sniper attacks.

After two days of fighting, most of the assailants were killed, captured or had blown themselves up. Nearly 100 others were also killed, most of them members of the Kurdish security forces. As the militants went on their rampage throughout Kirkuk, they broadcast a message from the loudspeakers of a local mosque: “Islamic State has taken over.”

Kirkuk, which is near some of the richest oil fields in northern Iraq, has been under the control of Kurdish forces for more than two years. The surprise attack by Islamic State showed that even while under siege in Mosul, the group could still sow chaos in parts of Iraq far from its strongholds. The offensive also demonstrated that even if it loses Mosul, Islamic State would go back to its roots as an insurgency entrenched in the rural Sunni Arab regions of Iraq — as its predecessor, al-Qaida in Iraq, did after losing several urban areas under its control.

Islamic State has been weakened over the past year, after intensive U.S.-led bombing and defeats by its opponents in Iraq and Syria. The group lost thousands of fighters, was forced to relinquish nearly half of the territory it once controlled and has been cut off from smuggling routes it used to move weapons and troops. But with every setback, it found new ways to adapt.

When it is eventually forced out of Mosul, Iraq’s second-largest city, Islamic State will want to prove its resiliency in neighboring Syria. One consequence of the Mosul battle has been to push the group’s fighters and leaders into Syria, especially its self-proclaimed capital in Raqqa. U.S. and allied warplanes have sporadically bombed the city and its outskirts for nearly two years. While U.S. Defense Secretary Ash Carter indicated on Tuesday that the coalition was making plans to attack Raqqa, even as it fought for Mosul, there is no significant ground force right now that could oust Islamic State from its Syrian stronghold.

American military officials said that in the days leading up to the Mosul offensive, some senior leaders fled the city, heading to Syria or other parts of western Iraq that are dominated by Sunni Arabs. “We’ve got indications that leaders have left,” Maj. Gen. Gary Volesky, the commander of U.S. ground forces in Iraq, said in a news conference in Baghdad on Oct. 20. “A lot of foreign fighters we expect will stay as they’re not able to exfiltrate as easily as some of the local fighters or local leadership, so we expect there will be a fight.”

U.S. officials said most of the leaders and fighters who fled were Iraqis or Syrians, who might have abandoned their weapons and shaved their beards so they could blend in with thousands of civilians who escaped from Mosul ahead of the battle. It’s more difficult for the thousands of foreign jihadis in Mosul to escape by hiding among Iraqi civilians, so they are making a stand in the city. Volesky, the top U.S. commander in Iraq, said the militants were burning forward positions in nearby villages, and withdrawing toward the city to fight behind a network of walls and trenches.

As the Mosul battle unfolds, Islamic State could become even more entrenched in Syria, especially in both Raqqa and the eastern city of Deir Ezzor. And as the group is pushed out of urban areas in Iraq, life for Syrians living under Islamic State’s control will become more difficult. Over the past year, the jihadis were already being denied access to revenue sources — including oil and gas smuggling, taxation and bank deposits — that brought in over $1 billion in 2014.

With the fall of Mosul, Islamic State would lose one of its most important profit centers. In 2015, U.S. officials estimate, Islamic State generated about $30 million per month from taxation and extortion in Iraq. In Mosul alone, the group made about $4 million per month in taxation, especially on salaries paid to workers by the central government in Baghdad. But with those revenues drying up as the militants lose territory and lucrative routes for oil smuggling, Islamic State’s leaders will likely impose harsher taxation and extortion schemes on Syrians living under their rule.

More broadly, the influx and entrenchment of Islamic State leaders in Syria will make it even more difficult to end the conflict there, which has expanded into a regional proxy war involving Russia, Iran, Turkey, Saudi Arabia, the United States and other powers. Russia and Iran, which are the two main backers of Syrian President Bashar Assad, are mainly targeting rebel factions opposed to Assad, rather than trying to dislodge Islamic State from its bastions. For its part, Washington does not intend to commit ground troops to oust the jihadis from Raqqa, and would instead rely on a coalition of Syrian Kurdish and opposition groups backed by U.S. airstrikes.

The Iraqi government and its Western allies are facing the massive challenge of rebuilding Mosul — and reaching a political accommodation with Iraq’s Sunni Arab community, so that militants will not be able to continue exploiting sectarian divisions. But there has not been much planning for the impact that pushing Islamic State out of Mosul will have on Syria.

Syrians too deserve to be freed from Islamic State’s brutal rule.

Mohamad Bazzi is a journalism professor at New York University and former Middle East bureau chief at Newsday.

In a time of both misinformation and too much information, quality journalism is more crucial than ever.
By subscribing, you can help us get the story right.