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.

They [ French] still have an open border in Europe. And they have a Europe which doesn't have an integrated intelligence system like we do in the United States.

We're not going to have a perfect batting average and it's important that Americans understand that.

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'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 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.

I think the refugee problem is Europe is vastly worse than we have in the United States.