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.

We need additional funding for more U.S. combat brigades in Europe. NATO needs to continue to modernize. It is starting to show with the Russians but these exercises are central to show that the alliance is firm, especially as the E.U. starts to have some weakness on the economic front.

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.

We have a Muslim population which is better off economically, better engaged, and less drawn to the fight in ISIS. But as we've seen in places like California and elsewhere, we still have a threat, even if smaller.

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.

Banning the burkini doesn't produce terrorists. But it does make the people who are already alienated, who are already disenfranchised, I many cases, economically disenfranchised in a place like France in many of those neighborhoods, and make them say, ah, ISIS's message is true and real.

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