I mean, when you get down to very low numbers of nuclear weapons, and you contemplate going to zero, how do you deal with the reality of that technology being available to almost any country that seeks to pursue it? And what conditions do you put in place?

I mean, when you get down to very low numbers of nuclear weapons, and you contemplate going to zero, how do you deal with the reality of that technology being available to almost any country that seeks to pursue it? And what conditions do you put in place?

I think that Vladimir Putin is certainly getting a lot of publicity for what the Russians are doing. And I'm not sure that's unwelcome to him. I think this is a guy who saw the U.S. basically come out against him in his reelection campaign in 2012. He saw the U.S. being behind all of the color revolutions in Eastern Europe and in Georgia and Ukraine and so on. So his view is the West has been interfering in his politics for years.

No president is well-served by groupthink or by everybody singing from the same sheet of music they think he's on.

If possible, to be in a position to announce who is going to step in as the interim immediately. And if possible, to announce who you're going to nominate to replace that person. For that to be somebody of impeccable integrity and reputation disarms a lot of the worst criticism that it's some kind of a power play. It's a professional approach to replacing a senior official, which is always going to get a lot of attention.

In my opinion, any future defense secretary who advises the president to again send a big American land army into Asia or into the Middle East or Africa should 'have his head examined,' as General MacArthur so delicately put it.

Even when I was at CIA, I'd go to visit foreign leaders and I'd say, 'You know, I'm not a diplomat. I'm just an old CIA guy'... I said, 'If I wanted to be diplomatic, I'd have been a diplomat.'