In June 2014, Mosul was seized by the Islamic State (IS), whose leader Abu Bakr al-Baghdadi soon afterward announced a caliphate from the city’s grand mosque. Now the caliphate is seemingly coming to an end.

Iraqi government forces took the eastern part of Mosul from IS on Jan. 24 after three months of fighting. On March 15, a spokesman for Iraq's Counterterrorism Service said 60% of the western part of Mosul is under the control of Iraqi security forces. The day before, Iraqi Prime Minister Haider al-Abadi had said the operation is in its final stage, pledging the defeat of IS.

But military victory in Mosul is just the beginning of a more complicated phase for Iraq. Disparate forces have so far come together to pursue the common objective of expelling IS from Iraq. With the imminent achievement of this goal, many underlying and preceding power struggles will likely re-emerge. Moreover, it should be borne in mind that various external powers — including Iran and the United States — have become greatly involved in Iraq’s security-related affairs and expanded their spheres of influence within the country since IS' 2014 onslaught.

One key question is who will step in to fill the power vacuum in post-IS Mosul. Will the United States revert to its previous retreat from the Middle East, or will it opt to reassure its regional allies by keeping at least a part of its current forces in Iraq? Will Iran seek to establish a presence in northern Iraq, either directly or through its allies?