The challenge in Mosul won’t be to defeat ISIS. It will be what comes after.

I have no doubt that coalition assets will, in the weeks ahead, do so much damage to the surviving Islamic State elements in Mosul that the battle there may well be less intense than many have feared. Thus, the most significant challenge in Mosul will not be to defeat the Islamic State; rather, it will be the task we faced there in 2003: to ensure post-conflict security, reconstruction and, above all, governance that is representative of and responsive to the people. All of this will have to be pursued largely by Iraqis, of different allegiances, without the kinds of forces, resources and authorities that we had.

Leaders of the various Iraqi elements will likely have their own militias, and there will be endless rounds of brinkmanship on the road to post-Islamic State boundaries, governing structures and distribution of power and resources. If those challenges are not enough, others will emanate from Iran and the Shiite militias it supports, from Turkey and Iraq’s Sunni Arab neighbors, from the Kurdish Regional Government that understandably wants to retain the disputed internal boundary areas that its peshmerga now largely control, and so on.

The effort in Mosul and Nineveh in the spring, summer and early fall of 2003 was very successful. Ultimately, however, it was undone by an inability to get Iraqi authorities in Baghdad to approve initiatives we pursued in reconciliation with former Baath Party members cast out of work by the Coalition Provisional Authority’s de-Baathification decree and in providing work for the tens of thousands of Iraq soldiers also rendered unemployed by the authority. The other ultimate challenge was the lack of clear direction and resources from Baghdad for their ministries’ activities in Nineveh. These failures meant that the Sunni insurgency ultimately intensified in Mosul, as it already had in the other Sunni Arab areas of Iraq. The Sunni Arabs in Nineveh came to see few reasons to support the new Iraq; indeed, they perceived many to actively or tacitly oppose it.