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.

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 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.

[Vladimir Putin] complimented him. That led Donald Trump to then compliment Vladimir Putin and to defend Vladimir Putin's actions in a number of places around the world.

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

Companies made these decisions about encryption when they were finding it very difficult to sell their products overseas because the [Edward] Snowden disclosures created the impression that the U.S. government was inside this hardware and software produced by them. They needed to do something to deal with the perception.