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?

Well, I've ruffled a few feathers at all the institutions I've led. But I think that's part of leadership.

Defense is not like other discretionary spending.

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.'

I wish I could set deadlines for the Congress, but that's just not the way the Constitution is written.

On the foreign policy side, there's the risk of being too spontaneous and too disruptive where you end up doing more harm than damage. And figuring out that balance is where having strong people around you matters.

One of the big changes in the Congress since I first came to Washington is that all of these folks go home every weekend. They used to play golf together; their families got to know each other, go to dinner at each other's homes at weekends - and these would be people who were political adversaries.