Six Factors Will Determine Whether Mosul Is a Success or a Failure

Without better preparations for the day after, the Mosul campaign could spark several wars within the war.

The Iraqi government, in coordination with Kurdish Peshmerga forces and with strong support from the United States, will begin operations to liberate Mosul from ISIS control as early as this week. Although the campaign is likely to succeed in wresting back control of Iraq’s second largest city, local and regional rivalries could quickly turn the tactical success into a strategic setback.
Without better preparations for the day after, the Mosul campaign could spark several wars within the war and cause great destruction in Mosul. Such a development would complicate stabilization efforts in Iraq, already marred by the virtually nonexistent reconstruction of devastated liberated Sunni towns, the minimal return of internally displaced persons (IDPs), and the fear of, and abuses by, Shiite militias. These factors point to continuing, and perhaps worsening sectarian tensions, with resurgence opportunities for ISIS or its successors.
Six issues in particular remain outstanding:
The Role of Shiite Militias.  Iraqi Prime Minister Haider al-Abadi initially declared that Shiite militias would not have a role in the operation to retake Mosul. Abadi’s decision was motivated, in large part, by events in the aftermath of the Fallujah liberation earlier this year. When Shiite militias surrounded the city, the predominantly Sunni population accused the militias of committing atrocities against local civilians. Some 600 civilians remain unaccounted for. Aggression by the Shiite militias overshadowed ISIS enormities and provoked Sunni outcries, which led to revenge attacks against Shiite targets. Three months after its liberation, only 500 IDPs had returned to Fallujah, a city that was once home to 350 thousand. Were Shiite militias to enter Mosul or “screen” fleeing civilians, one could expect complications on a yet larger scale. Sunni-Shiite tensions in Mosul could spread across Iraq and foment more extremism. 
But Abadi is now backtracking on his initial pledge to curtail militia involvement, saying that he has no choice but to include them in the Mosul operation. In this, he is likely responding to pressure from Quds Force Commander Qasem Soleimani and Shiite parties in Baghdad that are allied with Iran. For Iran, events in Mosul are important in the context of Tehran’s desire to see ISIS defeated, but also as part of its broader ambition to weaken hostile Sunni groups. Important too is the future of the Tel Afar district west of Mosul. Besides being home to Shiite Turkomen, Tel Afar can potentially offer Iran an outpost straddling the junction of Iraqi, Syrian, and Turkish Kurdish regions. Control of the district would allow Iran to project power on behalf of the Assad regime in Syria and harass the Kurdish Regional Government in Iraq.
During my recent visit to Saudi Arabia, Israel and Turkey, the leaders of all three expressed their concerns that Iran would use the occupation of Mosul by pro-Iranian elements to lay the foundation for a land corridor to Syria from which Tehran could destabilize or strike U.S. allies. Tehran may calculate that the involvement of pro-Iranian elements would counteract Turkey’s military deployment and secure the return of displaced Shiite Turkmen.
Turkey’s Role.  Iranian aggression is only one of several factors that may prompt Turkey to intervene. Turkey has an interest in defending Sunni Turkomen against atrocities by Shiite militias, and in ensuring that its Sunni Arab allies are not excluded from post-ISIS governance. Ankara is also wary of the PKK and Kurdish People’s Protection Units (YPG) presence in the Sinjar region between Mosul and the Syrian border. Iraqi Turkomen representatives echoed this uneasiness, demanding last week that the PKK be expelled from Turkomen areas.
Turkish President Erdogan has made it public, to Baghdad’s consternation, that he is prepared to support the entrance of Sunni Arab forces to protect the Sunni Turkomen community. A key Turkish ally is former Governor Atheel al-Nujaifi. Against Baghdad’s will, Turkey established a military base across the Tigris in Bashika, where its soldiers are training the Hashd al-Watani (or National Mobilization), a force of Sunni Arab volunteers assembled by Nujaifi.