What would degrading ISIS look like? Obviously, it would mean having its military units obliterated. There are 30,000 to 40,000 people, which is not a lot in the big scheme of things. You need to stop the recruitment to add to that, because the recruitment, much of it foreign, is making that number go up and up. The recent estimates of the CIA are that it's now at perhaps 50,000, and much of that has been through online recruitment. So you need to stop the recruitment.
I think you also need to change the tide domestically, and that means filling the political vacuum. I would say there are still people who despise the ideology, despise much of ISIS's rule, but who are saying, “If we get rid of ISIS tomorrow, what will come in its wake? Who's going to do the things like pick up the garbage, like provide electricity? More importantly, does this mean that we are now going to be under the rule of both the Abadi government and the Assad government?” That's not necessarily fathomable either, so you need to give them an alternative. That's really important in creating a narrative, and a real political option the day afterwards.
I really focus on this: what's the day after degrading ISIS? If you don't provide sustainable institutions that can fill that vacuum, it will just be another acronym that will fill that space.