The long-awaited military operation to retake Mosul from so-called Islamic State (IS) was announced by Iraqi Prime Minister Haidar al-Abadi on October 16.
It is considered to be the most complex military operation in the country since the American invasion in 2003. There will be significant political and humanitarian implications and challenges as a result.
Mosul is the largest city under the control of the IS in Iraq. The city fell to IS two years ago after the Iraqi army put up little resistance to the assault. The victory allowed IS to proclaim its alleged caliphate in Iraq and Syria.
Losing Mosul will deal the militant group a very strong blow. But, the defeat of IS in itself will not guarantee the city and its civilians a peaceful future.
This is because there are many parties that have teamed up with the Iraqi government to fight IS together, but if they manage to take back control of the Sunni majority city, the deep fissures and divergent political goals that separate these factions are likely to rear their head once again.
Divergent political goals
The battle amasses various parties to the conflict. They share the general goal of defeating IS but deeply disagree over other priorities.
The Iraqi army and Kurdish Peshmerga constitute the main fighting forces with the US-led coalition providing vital air coverage. In addition, there are an array of other important fighting groups, including the Shia mobilization forces and Arab tribal forces.
The Iraqi factions are deeply distrustful of each other. There are still serious territory disputes between the Iraqi central government and the Kurdish Regional Government.
There is also potential dispute about the way Mosul will be governed after liberation and the way civilians might be treated given the sectarian politics of Iraq that may put the lives of Sunni civilians in jeopardy.
Finally, the Turkish army is also involved in the fight, which has inflamed tensions between Iraq and Turkey. Iraq has accused Turkey of interfering in sovereign affairs.
Complex military operation
As the government-led fighters advance toward Mosul, retaking villages and making inroads in their mission, IS is showing signs of reverting to guerrilla warfare. Suicide attacks and sudden and coordinated attacks on disperse sites have been launched to divert attention and reduce the military concentration on Mosul.
The recent commando raid on the city of Kirkuk that killed 12 Iraqi administrators and engineers and four Iranian technicians is one example of desperate guerilla warfare tactics. Another example is the brief capture of the town of Rutba in western Iraq, hundreds of kilometres south of Mosul.
Imminent humanitarian catastrophe
The main challenge, though, facing the authorities in Iraq is the destiny of hundreds of thousands of civilians who are trapped in this battle. According to the UN, the humanitarian operation in Mosul is likely to be the single largest, most complex in the world in 2016.
Military operations along the western province of Anbar and the current Mosul corridors have already forced more than 230,000 civilians to flee their homes in search of safety.
In coming weeks, as the military campaign intensifies, an additional 230,000 people are expected to flee from cities and towns in Anbar and up to 660,000 people will be displaced along the Mosul corridor.
Once the military operation advances into the city of Mosul itself, 1.5 million people could be affected by the destruction of their livelihoods, displacement and shortage of essential services.
The majority of newly displaced families are moving towards areas under the control of the Iraqi Government and the Kurdistan Regional Government. Some civilians will also be forced to move to IS-controlled territory in the west.
International humanitarian agencies, the Kurdish Regional Government, and the Government of Iraq have already started planning for the imminent exodus of people displaced from Mosul by setting up camps and preparing them to receive hundreds of thousands of people. The scale of the humanitarian need is expected to be huge.
Supporting the humanitarian work in Iraq is critical to the lives and wellbeing of up to one million civilians. The UN launched a flash Mosul appeal requesting USD $284m to help support those affected in the current crisis in Mosul. But this appeal has only managed to raise half that amount to date.