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

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.

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

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.

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.

ISIS, in some cases like Paris, may actually try to direct. But what it's really trying to do is inspire. So its directed activities are these inspired attacks.

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.