The Vietnam War required us to emphasize the national interest rather than abstract principles. What President Nixon and I tried to do was unnatural. And that is why we didn't make it.

I have said there are three principles that should be followed. One, we should maintain the "one China" policy that every American president has articulated, including President Reagan. Secondly, we should make clear that we want a peaceful resolution. And three, Taiwan should not challenge that arrangement in a way that will provoke a conflict. Those are three perfectly clear principles. I haven't used any of the other slogans.

Diplomacy: the art of restraining power.

I would say the special experience of American wartime policy in the last 40 years, from Vietnam on, is that the war itself became controversial in the country and that the most important thing we need in the current situation is, whatever disagreements there may be on tactics, that the legitimacy of the war itself does not become a subject of controversy. We have to start with the assumption, obviously, that whatever administration is conducting a war wants to end it.

Whenever a new president comes in, people that are used to the previous president wonder if he has the same capacity.

A little uncertainty is good for everyone.

The members of the Islamic Staye have cut the throat of an American on television. This is an insult to the United States, which requires that we demonstrate that this is not an act that is free. I would strongly favor a strong attack on ISIS for a period that is related to the murder of the American.