As far as Paris goes, we don't know for sure yet how these guys communicate among themselves and how they communicated back to the ISIS leadership in Iraq and Syria, but I'm fairly confident we're going to learn they used these encrypted communication applications that have commercial encryption and are extremely difficult for companies to break - and which the companies have made the decision not to produce a key for.

What I want you to know is that 'Zero Dark Thirty' is a dramatization, not a realistic portrayal of the facts.

I want the vetting to be solid. But I also want to bring these people in because not bringing them in sends a message, right, to the Muslim world and plays into the ISIS narrative and the Al Qaeda narrative, right, that this is a war between religions. And we can't have that.

The thing we've learned from the last 20 years of counterterrorism is the significant value you get from removing leadership from the battlefield in degrading the organization.

Donald Trump didn't even understand, right, that [Vladimir] Putin was playing him. So, in Putin's mind, I have no doubt that Putin thinks that he's an unwitting agent of the Russian Federation, although Putin would never say that.

As far as Paris goes, we don't know for sure yet how these guys communicate among themselves and how they communicated back to the ISIS leadership in Iraq and Syria, but I'm fairly confident we're going to learn they used these encrypted communication applications that have commercial encryption and are extremely difficult for companies to break - and which the companies have made the decision not to produce a key for.

One great lesson from history we need to keep on re-learning. It is that sometimes your adversaries tell you exactly what they're going to do. How many times did [Osama] bin Laden say prior to 9/11 that he was coming after the U.S.? ISIS made clear that when they established their caliphate in Iraq and Syria, they were coming after the United States too.