American intelligence analysts are not as confidant as Iraqi and American politicians that ISIL (Islamic State in Iraq and the Levant) will be driven out of Mosul by late 2016. This pessimism comes from an analysis of how the smaller city of Ramadi was cleared of ISIL in December 2015 and how much more complicated the situation in Mosul is.
ISIL has controlled Mosul since June 2014 and most (all but about 700,000) of the original three million inhabitants have fled. Not only is that more than ten times what was in Ramadi before the final assault but the Ramadai population was almost all Sunni Arab. Mosul is a much more complex place with Sunni, Shia, Kurds, Turks and so on. Moreover Ramadi was on the Euphrates river in the relatively barren western Iraq while Mosul is on three times larger Euphrates (by water volume) river in an area with more vegetation and hills. This benefits the defenders. Finally Mosul is a much wealthier place than Ramadi, largely because of the local oil fields. This makes Mosul a much more valuable asset for whoever holds it.
Politics is more of an issue in Mosul than Ramadi. Mosul involves Sunni, Shia, Arab, Kurd and Turkish militias and each of these groups have still more factions. In Ramadi it was mainly Sunni ISIL versus Shia Iraqis aided by some pro-government Sunni. Finally ISIL had less than a thousand men in Ramadi for the final battle. Most of these defenders fought to the death. ISIL is apparently planning to have five to ten times as many fighters in Mosul for the final battle.
Nearly all civilians still in Mosul are openly hostile to ISIL, which is suffering from increasingly frequent and accurate air attacks. This is apparently the result of a more effective informant network in the city. Government forces south of the city and Kurdish troops (and non-Moslem militias) north of the city are preparing for the final attack, which the Iraqi government is saying will take place in mid-2016. This time a year ago Iraq was saying the attack would take place in mid-2015.
ISIL, and the Iraqi government, is most concerned with the Kurdish advance from the north because the Kurds have long had American air support. As more U.S. aircraft have arrived in the region, along with more American Special Forces to work with the Kurds, the Kurdish forces have become ever more deadly. Since early 2015 ISIL has been trying to stop the Kurdish advance and failed, suffering thousands of casualties (most of them dead) in the process. The Kurds are more vulnerable when they advance but because so many of the Kurds have years of combat experience and lots of U.S. training it is difficult to kill or wound enough Kurds to stop these movements. The Kurds are concerned about keeping their casualties low. This is good for morale, preserves the experienced fighters and recognizes the fact the Kurds have limited (compared to the Iraqi Army and Shia militias) manpower and want to conserve it.
All this also scares the Iraqi government because so many powerful players have a claim on Mosul. The Arab Shias are the majority in Iraq and control the government. Some of these Shia politicians are openly accusing Turkey of backing Sunni terrorists as part of a conspiracy to regain their lost (because of the British after World War I) Mosul province (the northern third of Iraq). The Turks deny this and there’s no “regain Mosul” movement in Turkey. What the Turks have done is negotiate a peace deal involving the Kurdish government of northern Iraq and Kurdish separatists in Turkey (the PKK). This was all done with little consultation from the Iraqi government. This annoys the Iraqis a great deal because the arrangement allowed the PKK gunmen to leave Turkey unmolested and move to Kurdish Iraq. One of the few things Iraqi Arabs agree on is the need to keep the Kurds weak and obedient. Since 1991 Iraqi Kurds have become autonomous and militarily powerful. The movement of thousands of armed PKK men from Turkey to northern Iraq makes it even more impossible to get the Iraqi Kurds back into line. Since 2015 that PKK deal has come apart and the Turks are once more at war with the PKK while remaining on good terms with the Iraqi Kurds.
The 2014 government defeat in Mosul was caused by a combination of corruption (leading to poor leadership and morale in the army and police) and years of Islamic terrorism in Mosul directed at the security forces. Without the crippling effects of corruption the army and police would still be in control. ISIL did not take the entire city right away. The Kurdish neighborhoods received reinforcements and support from the Kurdish controlled provinces to the north, although many Kurdish civilians fled north to avoid living in a combat zone. Over half a million civilians fled Mosul and many tried to get into the Kurdish provinces. That was a time-consuming process because the Kurds have kept Islamic terrorists out by imposing effective security measures and not falling victim to the lure of Islamic terrorism. The Kurds are not Arabs (they are related to the Iranians and other Central Asian Indo-European groups) and don’t care much for the Arabs (and vice versa). But business is business and Arabs who will behave are welcome to come visit, which a growing number of Arabs do if only to get away from the threat of Islamic terrorism for a while.
All these differences up north make the liberation of Mosul from ISIL rule much more complicated. Many Shia politicians play down these complications hoping that many of these problems will not be major obstacles to defeating ISIL. That may be so but long term the Iraqi government not only has to liberate Mosul but it also has to find a way to keep the peace once all the inhabitants have returned. That will prove more difficult that defeating ISIL.