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.

I worked with [Hillary Clinton] for four years very closely when she was secretary of state and I was at the CIA. I provided her - personally provided her some of the most sensitive information that the Central Intelligence Agency has.

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 [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.

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.

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.