My last visit to China as secretary, January of 2011, I told President Hu Jintao, just like this, "President of the United States wanted me to tell you that we now consider North Korea a direct threat to the United States." And it had no effect whatsoever.

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

My one concern is that Hu Jintao may overestimate how much power China has in Pyongyang. They have - they do have influence, and they do have companies, and they do have economic relationships that could make life much more difficult in the north. Their balancing act is, "How much worse can we make it in the north without creating that which scares us more than anything, which is a collapse in the north." And then what happens to all those nuclear weapons. So they're going to work very hard to avoid that.

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.

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.

When I was the director of Central Intelligence in the early '90s, I tried to get the Air Force to partner with us in building drones. And they didn't want to, because they had no pilots.

I will always be an advocate in terms of wars of necessity. I am just much more cautious on wars of choice.