Mosul was not the first city to fall to the self-proclaimed Islamic State of Iraq and the Levant (ISIL), but it was its capture that shocked the world into action. Over two years later, the much-anticipated Iraqi offensive to liberate Mosul from ISIL is in its early stages. Since the halt of the ISIL offensive outside Baghdad and Irbil and the engagement of U.S and coalition airpower, this battle and its result were preordained. Urban fights bring complications, and the coalition of forces advancing on Mosul should seek to minimize casualties and human suffering. But the moral and strategic imperative is to liberate the citizens of Mosul from the brutalities of ISIL rule, including vicious repression, regular executions and — for the minorities — organized rape.

The complex and varied groups of loosely allied military forces descending on Mosul have been the subject of a great deal of analysis, debate, and skepticism. While (almost) all these forces — willing to shoulder personal risk to liberate a captured city — should be applauded, this is not to say that there are not a host of serious concerns, both in the liberation and the aftermath. Mosul is a deeply complicated piece of terrain, both internally and in relation to external powers. There are serious equities that must be balanced or checked, even as Mosul’s citizens are liberated.

The forces encircling Mosul are primarily those of the Iraqi government — the Army, Federal Police, and Special Forces. Then there are the Kurdish Peshmerga, Sunni Arab forces trained by Turkey, and predominantly Shia Popular Mobilization Forces (PMF). There is also a small detachment of Turkish troops in the area that is not yet involved in the fighting.

Each of these last groups brings a particular set of political difficulties. While the Peshmerga have performed well since their retreat before ISIL in August of 2014, there are concerns that they might alter internal political boundaries by force of arms, rather than by political processes. In addition, tensions remain between the competing factions of President Masoud Barzani’s Kurdish Democratic Party (KDP) and those of the Patriotic Union of Kurdistan, dominated by the Talibani family. Most notably, the PUK accuses the KDP of stockpiling weapons for use against other Kurdish parties and being far more concerned about preserving power in the Kurdistan Regional Government than actually fighting against ISIL.

The Sunni forces assembled by former Ninewah governor Atheel Nujafi are widely seen as Turkish proxies — one of several points of tension between Ankara and Baghdad — and present the threat of a former governor being reinstalled by force. In addition, Nujafi is one of several Sunni figures named in internal documents from ISIL’s predecessor organization that indicate he cooperated with the group. This makes Nujafi — and by extension, his militia — a deeply flawed partner in the anti-ISIL effort.

Finally, the much-discussed Shia PMF bring at least the appearance of sectarian violence, even if this threat is almost always overstated for political reasons. However, while the majority of these Shia forces are patriotic Iraqis willing to fight ISIL and liberate their countrymen far from home, there is a disturbing minority of well-trained Iranian proxy groups (most notably the terrorist-designated Iraqi Hizballah) that could serve as spoilers. And just as detractors of the PMF overemphasize the actions of a minority of malign actors in their ranks, it is also true that the southern provinces that generate the PMF are sometimes overly forgiving of exaggerated but real sectarian-motivated persecution of Sunni civilians.

It is widely expected that only federal forces will enter Mosul, by order of Prime Minister Abadi. However, even if his command is observed, this still leaves plenty of room for human rights abuses and political maneuvering in the surrounding countryside, much of which is oil-rich and all of which is deeply contested by different ethno-sectarian groups. The possibility of mischief (or worse) by all of these forces should be closely monitored.

As in all of Iraq, the major tension in Mosul still rotates on two axes: the tensions between Iraq’s Kurds and Arabs and those between the Arab Sunni and Arab Shia. However, Mosul is further exacerbated by the presence of a wide variety of other groupings — Turkomen (both Sunni and Shia), Yezidi, Christians, Shabak, and others. The position of most of these communities has always been precarious, but ISIL’s actions exacerbated existing tensions and disrupted the prior equilibrium. Recreating a political arrangement that allows all these groups to live in peace with their neighbors while maintaining sustainable minority communities will be very difficult and perhaps impossible for some of the most devastated groups.

These minority communities have taken a one-two punch of disruption, first at the hands of ISIL in 2014 (not that their lives were perfect before), and then as political pawns between Kurdish and Arab interests in the Ninewah plain around Mosul as ISIL has been pushed back. There has already been one incident of violence between Kurdish Peshmerga and indigenous Turkomen Shia fighters. While cooler heads prevailed in that incident, the battle for Mosul could easily engage multiple flashpoints at once, leaving leaders unable to moderate the actions of their forces.

For these reasons and more, Mosul’s liberation will be far more complicated than the liberation of Tikrit, Ramadi, and Fallujah. All the cities liberated to date have been almost exclusively Sunni, requiring no particular attention to the makeup of the liberated populations. They were all also much smaller. Mosul, at its peak, was six to eight times the size of Fallujah.

The liberation of Mosul also takes place in the shadow of major disruptions in the Iraqi government. Iraq’s interior minister (Shia) resigned after ISIL’s Karrada peninsula bombing, and the highly regarded ministers of defense (Sunni) and finance (Kurd) were removed by parliamentary no-confidence votes in the past months, leaving Iraq’s three most important ministries leaderless. The increasing tensions within various ethno-sectarian groupings have further complicated Iraq’s already byzantine and dysfunctional politics. Former Prime Minister Nouri al-Maliki remains a prominent figure on the sidelines (playing a major role in the removal of the defense and finance ministers, for example) and appears to be exploiting the fracturing of Iraqi politics to assemble working issue-by-issue coalitions. One can hope that a relatively efficient operation to liberate Mosul will highlight Abadi’s effectiveness as a war leader and generate political capital for his Western-friendly government.

Iraq may give us far more cause for optimism when compared to Syria, but this should give the U.S. government cause to redouble its efforts rather than to become complacent. Despite the less-than-helpful influence of regional powers, Iraq has largely resisted and recovered from the worst outcomes in the region. Fortunately, as mentioned earlier, there is a Western-friendly government and it remains possible for friendly and responsible powers such as the United States and Germany to lend effective support to Iraq, even though issues of nationalism and sovereignty are never far from the surface.

We can expect Mosul to be liberated before the inauguration of the next U.S. president. This will deal a critical blow to ISIL, as they will have to revert — at least on the Iraqi side of the border — to acting as highly capable terrorist and insurgent group. However, this may leave them quite vulnerable to competing malign non-state groups who have also suffered under the ISIL boot, such as Iraqi neo-Baathists or even a returning al-Qaeda. ISIL will face a huge messaging problem after having lost all its governed urban areas, and it is difficult to “be the once and future caliphate.” Simply put, it doesn’t “resonate as much.” However, as the focus on ISIL will move — understandably — to its remaining strongholds in Syria, it is critical to keep U.S. attention on Iraq. Iraq has demonstrated that it is indeed an ally and has in fact carried the bulk of the burden in the anti-ISIL fight. While its democracy is fragile and imperfect, it remains among a very small group of democracies in the Middle East. It is very much in the U.S. interest to retain both a practical and an ideological ally in this critical — and fragile — region.

Douglas A. Ollivant is an ASU Senior Fellow in the Future of War project at New America. He is also a member of the Atlantic Council’s Future of Iraq Task Force. He previously served as Director for Iraq at the National Security Council. As a managing partner in Mantid International, he has business interests in Southern Iraq.

Image: U.S. Army photo by Spc. Jessica Hurst