The campaign to liberate Mosul from the self-proclaimed Islamic State (ISIS) has raised questions about what Iraq will look like once ISIS is defeated. The expulsion of the militants from Iraq will probably neither decrease the number of armed groups in the country nor limit the potential for violence there. Far from portending the end of Iraq’s current turbulence, ISIS’ demise could have the opposite effect, creating opportunities for violent competition in the areas that the militant group abandons.

There are a number of reasons why this is the case. First among these is the fact that ISIS has exacerbated the old grievances among the various groups living under its control in an attempt to play them off of one another. Next is the sharp increase in weapons and outside support that Iraq’s armed groups have received in recent years, in large part to equip them for the fight against ISIS. Even as Iran, Turkey, and other regional players compete for influence in post-ISIS Iraq, Baghdad will have to manage increased tensions at the local level, both between different ethnic and religious communities and within the particular groups that constitute them.

Shiite fighters during clashes with ISIS militants near Kirkuk, March 2015. Ako Rasheed / REUTERS

DIVIDED AND CONQUERED

Tensions between Iraq’s ethnic and religious communities are on the rise. In the disputed territories in the northern parts of Diyala Governorate, the eastern portions of Nineveh Governorate, and in the city of Kirkuk, which was captured by Kurdish fighters after the retreat of the Iraqi army in the face of an ISIS offensive in the summer of 2014, the friction between Arabs and Kurds, in particular, is increasing.

In recent weeks, Kirkuk has again come under attack by ISIS fighters seeking to divert Iraqi forces from their assault on Mosul. According to Sheikh Burhan Assi, an Arab member of Kirkuk’s provincial council, after one such attack in October, Kurdish militants used the amplifiers in mosques in several Kurdish neighborhoods to demand that internally displaced Arabs leave the city—a sign that the Kurdish militants considered the Arabs to have ties to ISIS.

The region’s Arabs are not pleased with the extension of Kurdish influence that the past few years have brought. At the moment, they are represented mostly by tribes and have not yet organized into militias. But that could easily change once ISIS-held territories are liberated, encouraging more groups to jostle for power and thus generating more violence.

As tensions between Kurds and Arabs have intensified, so too have the old disagreements between Shiite and Sunni Arabs. Those squabbles existed well before ISIS’ rise; in places where ISIS has been defeated, they are growing worse. Consider the case of Suleiman Bek, a medium-sized town near the border between Diyala and Salah ad Din Governorates that was recaptured from ISIS in the second half of 2014 by Iraqi Kurdish fighters and Shiite militiamen. Nearly two years after the area’s liberation, armed Shiite groups are still preventing many of the Sunni civilians who fled the fighting from returning to their homes, leaving them to languish in camps for the internally displaced. “I followed all required procedures to return people to their homes, but at the end of the day I could not make the militias comply with the Iraqi government’s regulations,” Taleb Muhamed, a director of the sub-district, told us. The local government’s impotence reflects a broader dynamic in Iraq: Baghdad’s reliance on Shiite militias has allowed those groups to gain undue power.

The war against ISIS has not eliminated the internal rivalries of Kurdish groups.

The divisions between Shiites and Sunnis have spilled over into Turkmen communities, as well. The town of Tal Afar offers just one example. When ISIS captured Tal Afar in June 2014, many Shiite Turkmen escaped, and many Sunni Turkmen joined the militant group, looting the town and selling off the property of some of the Shiites who had fled. Tal Afar is still under ISIS’ control; when it is eventually liberated, the tensions between Shiite and Sunni Turkmen could come out into the open.

TROUBLE IN KURDISTAN

Although the war against ISIS has unified the Middle East’s various Kurdish groups against a common enemy, it has not managed to eliminate the internal rivalries among them. That is especially apparent in Sinjar, where the competition between groups affiliated with the Kurdistan Worker’s Party (PKK) and the Kurdistan Democratic Party (KDP), the dominant party in the Kurdistan Regional Government, have increased since ISIS was pushed out of the area in November 2015. The PKK was among the first groups to respond to ISIS’ actions in Iraq and to the terrorist group’s genocide of Yazidis in the area around Sinjar—a position that allowed it to significantly deepen its presence in the area.

Before the war with ISIS, the area around Sinjar was disputed: it was dominated by the KDP, but PKK-affiliated groups could not afford to abandon it either, since it provides a vital connection between Iraq and groups allied with the PKK in Syria’s Kurdish territories. Now that the PKK has gained strength in the wake of the Sinjar operation, the competition between it and the KDP has become even more flammable. Both sides are accumulating weapons and, in recent months, have exchanged a number of harsh political statements.

The internal disputes among Iraqi Kurds have also polarized the Yazidi community, which had not been militarily organized before the war with ISIS. Today, Iraq’s Yazidis are represented by a number of armed groups: the pro-PKK Protection Force of Sinjar (or HPS) and Sinjar Resistance Units (or YBS), and the pro-KDP Yazidi units in the Peshmerga and the Shingal Mobilization Force, whose main objective is political autonomy.

Finally, there is the competition between two of Iraqi Kurdistan’s main political parties, the Patriotic Union of Kurdistan (PUK) and the Kurdistan Democratic Party (KDP). The tension between them is especially concerning because each party controls its own factions within the Peshmerga and because they may be tempted to compete for power in recently acquired territories. There are already signs that such competition is brewing. In September, for example, the KDP-dominated Kurdistan Regional Government reached an agreement with the Iraqi federal government over the sale of oil extracted around Kirkuk. But the PUK’s leaders did not accept the deal: they sent a letter to Iraqi Prime Minister Haider al-Abadi demanding that Baghdad discuss such issues with them instead of with members of the KDP.

Kurdish fighters at Mosul Dam, October 2016. Youssef Boudlal / File Photo / REUTERS

INFIGHTING AND INSTABILITY

Sunni Arabs remain the least well-organized community in Iraq, but that could change once ISIS, which many Sunni Iraqis have joined, is defeated. As is the case with Iraq’s Kurds today, that could lead to infighting in the near future.

Mosul is already home to several Sunni Arab armed groups. At the moment, those groups are working together against a common enemy. But in part because they receive support from different sources (Hashd al-Ashayari is backed by the Iraqi government, for example, whereas Kataib al-Mosul is sponsored by Turkey), they will likely compete for power once ISIS is defeated.

The desire for revenge against perceived ISIS collaborators and sympathizers also raises the chances of infighting among Iraq’s Sunni Arabs. Some Sunni Arabs have joined ISIS and fought against the members of Sunni tribes to which they do not belong. In such cases, once ISIS is defeated, the aggrieved tribes could pursue full-scale conflicts with the tribes of the perceived offenders. The case of the al-Ubed and al-Bayat tribes, in a village near the town of Hawija, points to this possibility. In late 2014, a teenager from the al-Bayat tribe joined ISIS and was sent to kill a former Iraqi policeman who happened to belong to the al-Ubed tribe, according to a farmer with close ties to the al-Bayat tribe but declined to give his name, fearing ISIS reprisals. Worried that the al-Ubed tribe would seek to avenge the man’s death after the village’s liberation, the teenager’s extended family fled the village when Iraqi forces started pushing the militants out of the area. And then there are the myriad other small disputes that will arise among Sunni Arabs once ISIS is defeated, such as conflicts over the ownership of property based on ISIS-issued titles. These, too, could lead to violence if they are not settled properly.

As for Iraq’s Shiite Arabs, like Mosul’s Sunni Arabs, they are represented by a variety of armed groups that receive support from different sources, chiefly Iran and the Iraqi government. The struggle among them has already produced violence in territories liberated from ISIS. In June, for example, members of the Badr Organization and Asaib Ahl al-Haq, both Shiite militant groups, fought for about a day in the city of Tuz Khurmatu, leaving several people wounded. The violence was set off when Asaib Ahl al-Haq kidnapped a member of the Badr Organization, and it ended only after Asaib Ahl al-Haq withdrew from the area.

That Iraq will build a strong and united military to resolve these problems seems unlikely, thanks in part to Baghdad’s dependence on Shiite militias. Yet so long as Iraq’s central government lacks the power to enforce order on its own, the country will be prime territory for nonstate armed groups. That is troubling, since the more armed groups appear in Iraq, the harder it will be to bring the country’s competing factions to the table to reach political solutions to their problems.