I'm concerned, too, about ISIS' ability, right, to infiltrate people. But we have got some very effective, robust processes for vetting people. We brought in thousands of Iraqi refugees after the Iraq War. Not a single one has ever turned out to be a terrorist because the vetting was so good.

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.

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.

One of the lessons we've learned from the last 25 years of terrorism is that groups that have safe havens are able to develop external attack capabilities in a way that groups that don't have safe havens are not. So we need to find a way to squeeze them significantly in their safe haven. Taking away territory that really matters to them is really, really important because it prevents them from focusing on external attacks.

Look at it from [Vladimir] Putin's perspective, right. He's a trained intelligence officer, worked for the KGB, very talented, manipulated people much smarter than Donald Trump. He played this perfectly, right. He saw that Donald Trump wanted to be complimented.

The [Edward] Snowden disclosures created this perception that people's privacy was being put at significant risk.

If you were watching CNN, they were saying the NSA is listening to your phone calls. It's reading your emails. When you call your grandma in Arkansas, the NSA knows. All total bulls - t. They made the public more concerned about the privacy issue than the legitimate facts should have done.