You've got a huge American population, you've got a small, small, small subset that is radicalized, and you have an even smaller subset that actually takes action. And you can't cover everyone who has some contact, someone bad. What you need is offense overseas, defense at home with intelligence and law enforcement, and really deep engagement with these communities.

I think the vetting we have for refugees is vastly better than the Europeans have.

I think we have started accelerating over the past years. It's a modernization of NATO. It's at air, it's at sea, it's undersea, it's in cyber. Estonia in 2007, hit by Russian cyber-attacks. So what you see there with those exercises are critical.

When you do have really tapped out resources that cover so many investigations, it can help you move through and discard some faster.

We can't be French and Muslim at the same time. And that's exactly what ISIS wants that population to think.

I don't think bulk data collection was an enormous factor here, because generally, that deals with overseas calls to the United States. But what bulk data collection did was make the process more efficient. So there were no silver bullets there.

You have the intelligence front and the engagement front. On the intelligence front, the French are better than many of their European counterparts. But they are really challenged in two specific ways.