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.

You have to have a military and intelligence approach to removing leadership that results in rapid frequent removals from the battlefield. It's got to be one, two a week, not just one or two every three or four months.

Do I believe Edward Snowden contributed to the rise of ISIS? Yes. Would they have gotten there without the help he provided them? Probably. Would they have been able to conduct this attack in Paris without him? Maybe. So the honest answer is I don't know.

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.

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.

From Mr. [Donald] Trump's perspective, right, he simply heard [Vladimir] Putin compliment him. He then responded by complimenting him. He never thought that he might be being played.

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.