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.

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

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.

[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.

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.

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.