The offensive to drive the Islamic State movement (ISIS) out of Mosul, the largest city it has held, is being led by Iraq’s government, with support from the United States and the international coalition against ISIS. But Iraqi groups fighting ISIS around Mosul represent ethnic or religious communities that are continuing old battles for land and power. Several of the rival groups get support from the governments of Iraq, Turkey and Iraq’s autonomous Kurdish region.

With Iraqi forces battling to re-take control of Mosul, “unfortunately there is not a plan for the day after.” —Osama Gharizi, U.S. Institute of Peace

The stakes could hardly be higher. The future of the Iraqi state is likely to be shaped by how well it can stabilize Mosul and the ancient region it commands along the Tigris River. The province, Nineveh, holds a welter of ethnic communities—Arabs, Kurds, Turkmen and Assyrians—many of which include Shia and Sunni Muslims, Christians, Yazidis, Shabak and other religious groups. These groups at times have lived peacefully for generations, but also have rivaled each other for influence, often with outsiders’ support. Now Iraq’s central government, the autonomous Kurdistan Regional Government and Turkey are allied with rival groups in a contest over future control of Nineveh Province. For months, a chorus of Iraqi and Western analysts urged Iraq’s government and its international backers to ensure preparations to stabilize the province politically before the Mosul offensive began.

“Unfortunately, there is not a plan for the day after,” according to Osama Gharizi, a U.S. Institute of Peace program officer in Iraq who supports local conflict-resolution efforts. “This is something that we’ve been urging, that others have been urging—that there needs to be a political agreement on what happens beyond the military operation,” Gharizi said in an e-mail from Erbil, Iraq. “And there hasn’t been real movement on that.” About two weeks before Iraq’s government launched the military offensive, it announced the formation of a high-level council to coordinate responses to issues that arise around Mosul following an ouster of ISIS. But “the seats on that council are vacant, no one knows who’s going to be on it,” Gharizi added in an online briefing with USIP colleagues. “That is the extent of a plan.”

The risk of conflict heightened over the weekend around Tal Afar, a historic center for Iraq’s Turkmen, who have cultural ties to, and support from, Turkey. Tal Afar is predominantly Shia, and militias made up largely of Shia fighters, known as Popular Mobilization Forces, announced a drive on Tal Afar. Turkish Prime Minister Recep Tayyip Erdogan warned that Turkey would respond.

Mosul: A Map of the Post-ISIS Conflict

The main groups fighting ISIS support various options for the future status of Mosul and Nineveh province. Iraq’s government would retain Nineveh’s status as one of the country’s provinces, offering  it greater powers under a 2008 law on decentralization that has not yet been applied. The Kurdish Regional Government prefers to divide Nineveh, absorbing part of it into the Kurdish region. Turkey, which once ruled Mosul and asserts an interest in helping to shape the province’s status, opposes any expansion of Kurdish influence and backs a local militia that would make the province an autonomous region.

Within Iraq, “there have been no formal discussions” and “no political agreement reached on the future of the province,” said Gharizi. Amid that political conflict, at least four groups now are fighting to wrest control of the area from ISIS:

—Iraq’s army and police. The Iraqi state military are at the center of the drive on the city of Mosul, and the government in Baghdad says those army troops, with police, will be the only forces to enter the city. The Iraqi forces are trained and advised by thousands of U.S. and other coalition troops, and supported by a U.S.-led air campaign. Following reports of human rights abuses by government forces in other areas recaptured from ISIS, Iraqi officials have vowed that the army and police will protect Mosul’s civilians. But police officers waiting to enter the city have told reporters they plan revenge attacks on anyone they suspect of having supported ISIS.

—Kurdish Pesh Merga. The Pesh Merga is the force of Iraq’s autonomous Kurdistan Regional Government (KRG). The KRG agreed with the central government to keep its forces outside of Mosul city, in areas to the east where they now hold territories. The Kurdish authorities may use their troops’ presence to strengthen their position in disputes with the central government over control of several areas, in Nineveh and around Kirkuk, to the south.

—Popular Mobilization Forces. The Popular Mobilization Forces are militia groups that were gathered under the formal authority of Iraq’s Interior Ministry in 2014 to buttress the army and police for the fight against ISIS. Most of the forces are Shia Muslim groups, many of which existed beforehand and have had training and support from Iran. In the Mosul region, the presence of the Shia militias may strengthen the Iraqi government in its plan to retain Mosul as an ordinary province. Turkey says the militias’ presence will be harmful to the Sunni Arab and Turkmen population.

—Sunni tribal forces. Former Nineveh governor Atheel Nujaifi has built a militia of Sunni Arab tribal fighters supported and trained by Turkey and called the Nineveh Guard. Nujaifi and his allies say Nineveh should be made an autonomous region under Iraq’s constitution. In a sign of the divisions in the Iraqi coalition against ISIS, an Iraqi court issued an arrest warrant for Nujaifi shortly after the Mosul offensive began, reportedly over a complaint that he had facilitated the presence in northern Iraq of Turkish forces. Nujaifi’s Nineveh Guard is rivaled by a separate Sunni militia that includes fighters from the prominent Jubouri tribe, armed and backed by the central government.