At the end of 2014, Iraqi government officials and U.S. allies began planning a massive operation to retake control of Mosul from the Islamic State (IS), but the focus quickly shifted to Tikrit, which Iraqi forces retook in late March 2015. Following this victory, talk began of a wide-scale attack that would be launched in April or May 2015 to retake Mosul. The force was to include about 25,000 soldiers, primarily comprised of Kurdish peshmerga forces and five brigades from the Iraqi army. However, once again attention was diverted away from Mosul after the Islamic State took control of the city of Ramadi on May 17. The Iraqi government was forced to dispatch more troops to Anbar, considering control of this province more important for the security of nearby Baghdad and the holy Shia city of Karbala. But as the fighting fronts between Islamic State and Iraqi security forces have stabilized around the city of Ramadi, an operation to retake Mosul is again in discussion. 

In early fall of 2014, when government officials began to establish the “Mosul liberation force,” they had 4,500 volunteers, most of whom were former police officers who had fled the city. By early 2015, there were still only 10,000 registered recruits—modest in comparison to the 52,000 security service members in Mosul before it fell. The Mosul liberation force obtained promises of support, armament, and training from the federal government, the Kurdistan Regional Government (KRG) and the U.S. military. A joint committee of these organizations was formed and first met in Erbil on December 9, 2014 to agree on a plan to retake Mosul, with the United States providing air support. At the time, Iraqi officials estimated that they would need a few months to take the city. 

Yet this committee did not form any concrete plans for the force, and it is unclear if any have since been developed. Meanwhile, Mahmoud al-Surji, the spokesman for the (majority-Turkmen) National Mobilization Forces, called on volunteers in Nineveh to form two new military divisions in preparation for an operation to retake the city. These divisions would be made up of displaced residents of the province and residents of other areas liberated from the Islamic State, and they will be trained in camps south of Erbil. 

But various military and political obstacles stand in the way of any significant effort to retake Mosul. The first is the city of Baiji, 200 kilometers (125 miles) south, linking IS fighters in Anbar to the Syrian province of Raqqa—which supplies fighters and stores weapons for the Islamic State. It would be difficult to retake Mosul without first fully retaking Baiji, as this would mobilize military forces to the region and cut off the Islamic State’s supply lines. But though Baiji is smaller than Mosul, it has exhausted the Iraqi Army, the Popular Mobilization Forces, and tribal fighters attempting to retake it—despite the support of coalition aircraft. The battle for control of Baiji and its oil refineries is still ongoing, and the Islamic State recently regained some regions of the city. This prompted leaders of the ruling Iraqi National Alliance to call for a review of the adopted plans, worried that the losses witnessed by those carrying out operations in the city could affect the morale of fighters.  
 
The offensive forces to retake Mosul will be hard-pressed to gain control of the city, particularly because the Islamic State has reinforced its defense with minefields and explosives-laden buildings. Although it is difficult to determine the number of IS fighters currently defending Mosul (given the group’s ability to maneuver a reserve of troops from the Syrian city of Raqqa to Anbar), estimates range from 1,000 to 30,000.  Furthermore, Kurdish officials estimate that the Islamic State has a total of 200,000 fighters that they could draw upon to defend Mosul—though this figure is roughly seven times the CIA’s estimate of 31,500. In customary military contexts, an offensive force should be three times as strong as the expected defensive force. Retaking the city will require fighting on the streets of Mosul, something the Islamic State excels at. By contrast, fighting in residential neighborhoods would neutralize the coalition’s air power advantage, make offensive forces more susceptible to IS mine traps, and enable some local residents to fight on the Islamic State’s side. 

National Guard Forces that consist of residents of the province could secure the city, but only if the relevant draft law is passed in the Iraqi Parliament—which is still reluctant to create this Sunni force. In the absence of such a force, Mosul residents, most of whom are Arab Sunnis, remain generally opposed to intervention by the Shia-led regime forces and the Popular Mobilization Forces as an alternative. The majority of Sunni Arabs in Mosul feel that the Popular Mobilization Forces, if part of the campaign to retake the city, would seek revenge on them under the pretext that they supported the Islamic State. According to an Amnesty International report, this has already happened in Baghdad, Samarra, and Kirkuk. As a result, the participation of the forces in an operation to retake Mosul would be opposed by local residents and allow the Islamic State to rally more locals around them to fight on their side. 

For the same reasons, locals also oppose the peshmerga forces, which the United States would prefer be the primary force to retake Mosul. Furthermore, peshmerga forces’ operations to retake control of various regions have been marred by allegations of violations against Sunni Arabs in Arab villages. These include attempts to impose a fait accompli—deeming the land the possession of whoever liberates it. Growing Kurdish nationalist ambitions to annex more Arab land will fuel further conflicts over land and resources that have been parts of the decades-long conflict between Arabs and Kurds.

Such issues in putting together an offensive force make the operation to retake Mosul seem complex from a military standpoint. But retaking the city would require even bigger political solutions, including putting an end to the Popular Mobilization’s marginalization of the government in decisionmaking. This would allow Prime Minister Haider al-Abadi to move forward with political reforms promised to Arab Sunnis, rebuilding mutual trust and motivating them to get involved in the fight against the Islamic State. 

And once forces reach Mosul, they face significant challenges in building local resident networks to oppose the Islamic State. In Anbar and Diyala, the anti-IS coalition has been able to rely on the tribal Sahwa (Awakening) Councils formed by the United States in 2006 to expel Al-Qaeda in Iraq, which later became the Islamic State, from the cities. However, Nineveh Province, where Mosul is located, has few active Sahwa, and there is no preexisting tribal force comprising residents of the province to fight the Islamic State. 

Even once the city is taken, there is no force available to ensure it does not fall into the hands of the Islamic State again. An effective local force is necessary to rein in local youth disaffected by the government. They would prevent the car bombings, assassinations, and organized crime that were rampant in Mosul before the Islamic State seized it last year. Such acts contributed to the allegedly warm welcome that some Mosul residents gave to the Islamic State, as well as the renewed pledges the city’s tribes made to the organization following its losses in Tikrit. 

For these reasons, the United States and its allies have limited options to retake and hold Mosul. They can exert pressure on the Iraqi parliament to move forward with forming the National Guard Forces or circumvent the government’s opposition to arming Sunni tribes, either of which might be able to catch up to the Islamic State’s growing recruitment and armament. A large U.S. or multinational ground incursion might be the only alternative.

This article was translated from Arabic.