I had no difficulty as Secretary of Defense moving from the Bush administration to the Obama administration.

Congress is best viewed from a distance—the farther the better—because up close, it is truly ugly. I saw most of Congress as uncivil, incompetent at fulfilling their basic constitutional responsibilities (such as timely appropriations), micromanagerial, parochial, hypocritical, egotistical, thin-skinned and prone to put self (and re-election) before country.

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?

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.

It's a very broad and not very well-disguised effort of Russians to create questions about the legitimacy of these Western elections. And, I think, this is very K.G.B.

There is no international problem that can be addressed or solved without the engagement and leadership of the United States and everybody in the world knows that, its just fact of life. So sometimes I think we could conduct ourselves with a little more humility.

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.'