The fact that there are now many entities that may have some loose affiliation with a former core Al Qaeda - or who have decided to fashion themselves as an affiliate or follower in the Al Qaeda jihadist tradition - as well as groups that are just inspired by the concept that they could also be the perpetrators of mass killing, means that there is a spectrum of threats.

Terrorism is really the only existential threat to America as we know it - as a free country that plays a leading role in the world.

I think we should be organized in something called an Alliance Against Nuclear Terrorism. In the same way that NATO was the great alliance of the Cold War and served a great purpose then, we need now, in the war on terrorism, a new alliance, the mission of which would be to minimize the risk of nuclear terrorist attacks, and the members would agree to sign on to the gold standard.

The absence of a focal enemy, which is what the Cold War had provided; the complexity of the developments that are occurring that mean that the world is just extremely complicated - lots of different and competing stories and strands; the continuing reality of megaterrorism; and the dysfunctionality of our politics that has neglected the foundations of the U.S. role in the world; have altogether left us somewhat confused.

Putin needs to understand and feel in his gut that if the Chechens get a nuclear bomb, they're going to Moscow first, they're not coming to New York.

I think the election of Trump was an expression of what happens in ruling powers as they become alarmed.

And I hope that we can learn the lessons of the past in looking at the current challenge that China poses to a ruling America.