[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.

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.

I'm really curious as to the actual structure of the Emni [the intelligence unit that handles foreign attacks]. And Abu Muhammad al-Adnani, the head of it. There are so few pictures of him. We don't even really know what he looks like. For somebody with this outsized influence projecting murder abroad, you'd think that we would know a lot more by now. And then the role of the hostages.

[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.

We know that Muhammad waged war against the Qurayshi tribe, his own tribe, and it's from that conflict that much of the concept of jihad and verses that ISIS now uses to justify beheadings come from. A young man just told me that he went back and read this carefully [and saw] the prophet and his people were fighting the Quraysh because they were not allowing the prophet and his people to practice their religion.

First, I would say, is ideology. I have never spoken to any member of these groups, not just ISIS, but also Al Qaeda, Shabab, etc., who wasn't driven by the ideology. Beyond that, a lot of people are wounded in some way - they've fallen out of society in some manner. All of the ones I've spoken to seem to have veered off course from lives we consider acceptable and successful. Of course, there are others like Osama bin Laden, who was a wealthy and successful businessperson.

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