I'm actually genuinely optimistic about the United States and what's possible in the United States. And when you're out here, you see Americans across racial and economic and socioeconomic lines working together. And you maybe get a little bit less cynical than when you sit in the seat of kind of the epicenter of it all.

Fortunately, I started very young, so I read music very well. And my favorite composers to play are Brahms and Mozart.

Multilateral diplomacy is hard. It's slower, it's tougher, it's a bigger slog. I've learned that sometimes the things you'd most like to do something about, you really have difficulty unless the international community really mobilizes.

But we do have confidence in our institutions. We are not Russia. We have an executive that is constrained. We have a legislature that is real. We have a press that is free. We have courts that are independent. This is not Russia.

If you're always in the company of people who agree with you, you're going to think of people who don't agree with you as venal or stupid. I constantly tell my students that if they're in the company of people who always say "amen" to what you say, find other company. And that is the source of illiberalism, when you are unable to listen to someone who thinks differently. That's when democracies are in trouble.

I'm actually genuinely optimistic about the United States and what's possible in the United States. And when you're out here, you see Americans across racial and economic and socioeconomic lines working together. And you maybe get a little bit less cynical than when you sit in the seat of kind of the epicenter of it all.

There was no silver bullet that could have prevented the 11 September attacks. There was nothing demonstrating or showing that something was coming in the United States. If there had been something, we would have acted on it.