People who have left the group talk about how a religious inspiration took them to ISIS. It was their feeling of being marginalized as Muslims in the society where they were living, and then buying into the promise of a caliphate and of a Muslim land that is governed as in the time of the prophet. I have yet to meet anybody, or speak to anybody, who was not religiously motivated at some level.

[People who have left the ISIS] say that there comes a moment when the inconsistencies and apparent hypocrisies of their sheikh lets them down, and they begin rereading scripture and find ways that vouch for a nonliteralist reading of the Koran.

If we cover a court case involving a murderer, we would still seek out the side of that murderer, even as we realize that what people say is going to be self-serving.

It seems to me that a 9/11-style attack is impractical.

One of ISIS' biggest propaganda coups was the beheadings of the aid workers and journalists. Is [Emni], the group that is exporting fighters overseas, also the one that was holding James Foley and John Cantlie and Kayla Mueller?

It's become extremely difficult to speak to active ISIS members now. I was speaking to them in 2015, and the last one was killed in a drone strike.

They're implementing what was the strategy of Al Qaeda, which was to have attacks of different levels simultaneously. ... So the idea is, on the one hand you have these spectacular attacks that take months to plan, and others like Reda Hame, a French national, who went to Syria and was there for about a week, given a couple of days of target practice and one day of encryption training, sent back and arrested almost immediately.