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

I think in the policies that have been followed since the president Donald Trump came into office, there really hasn't been any slack cut for the Russians. And I think one of the things that has surprised people has been that the relationship between the United States and Russia has in fact deteriorated since the election.

If there's ever an example that military power alone cannot be successful in Afghanistan, I think it was the Soviet experience.

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.

What I know concerns me. What I don't know concerns me even more. What people aren't telling me worries me the most.

I think that Iran with a nuclear weapon is extremely destabilizing. I think it could precipitate a nuclear arms race in the region.

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.