Summary
Mosul has gained a certain symbolic significance in the fight in Iraq against the Islamic State. Iraq's second-largest city and the biggest bastion of the Iraqi Sunni Arab population, Mosul has served as a strategically important source of manpower and finances for the Islamic State since the group gained control of the city in June 2014. However, it is only one piece of the Islamic State's territory, and its loss would not be an existential blow to the group or immediately end the larger fight against the Islamic State. Nevertheless, numerous actors, particularly Baghdad and Washington, are using the impending battle for Mosul as political capital to mark the reversal of Islamic State gains. Though Mosul will likely be the staging ground for the next large-scale battle in Iraq, there are several key steps that must be taken before an offensive can be launched.
Analysis
An anonymous source at U.S. Central Command recently released the details of the battle plan and organization of forces that the United States and its partners are aiming for, with the goal of launching the offensive by April or May. The details outline a plan for an Iraqi security force consisting of 20,000-25,000 troops to advance from the south to retake Mosul while Kurdish peshmerga forces contain the city from the west, north and east.
Phase One: Train Troops and Contain the City
The first phase comprises the training of appropriate troops and the containment of Mosul. Many steps have already been taken toward executing this phase: The peshmerga forces have maintained steady offensives around Mosul while cutting off the city's main supply line from Tal Afar, and the United States and its coalition partners have been training Iraqi troops. However, the training is far from complete.
Pulling together a unified force of disparate fighters numbering in the tens of thousands within a month is ambitious, to say the least, particularly when many of these groups collapsed last year and hold conflicting interests or historical enmity toward each other. Washington has been quite vocal about taking the time needed to accomplish this goal before launching the offensive against Mosul, but Baghdad — facing pressure from its citizens to show that the army is winning the fight against the Islamic State — has been pushing for the fight to begin as soon as possible.
The composition of the fighting force also poses an issue for planners. While the peshmerga, Iraqi army, Shiite militias and some Sunni tribal elements have been able to work together without too much friction thus far, the overuse of such forces in proximity to each other could result in infighting and collapse. A mixture of Sunni tribal forces and Shiite militias would be especially volatile, and one that the U.S.-led coalition seems to be trying to avoid by having them work in separate areas. In the case of Mosul, these groups have been excluded entirely; instead, planners rely on peshmerga forces to block in the city and conventional Iraqi forces to form the maneuver element.
Phase Two: Push North and Seize Mosul
Regardless of the difficulties or pitfalls in Phase One, certain events must happen on the ground before the offensive can begin. First, training must be completed and forces must be shipped north toward Mosul itself. Because the Islamic State holds multiple towns and villages south of Mosul along the Tigris River Valley, it remains to be seen how military planners will address those areas in their plans. One option would be to contain enemy forces within the cities while allowing the main force to bypass them and head straight for Mosul. While this tactic would save time, it would also cost manpower that could not be used in the main battle. Another option would be to methodically clear the valley and displace Islamic State fighters from all of their positions. This would preserve a larger force for the battle at Mosul, but it would likely cost time and lives. One of these options must be implemented to protect the supply lines and flanks of the forces that take Mosul, and until a large force arrives at the city's doorstep, no serious offensive can begin.