President Obama has made the Asia Pacific region a focus of his foreign policy, and Vietnam - a large, growing economy in the heart of Southeast Asia - is critical to those efforts.

I think one of the critiques of me is that I thought I knew it all. But I was learning from the enormous resources available within the U.S. government who have a very different view of the world than many of the people commenting on foreign policy from outside of the government.

When it comes to Israel's security, our military and intelligence cooperation, that's off limits. That's protected. That's sacrosanct.

Talking and diplomacy is often seen as a concession in America, in a way that it is not in other places.

Walking is my main method of relaxation. I don't go over my lines or try to solve the world's problems, I just enjoy the scenery and the wildlife.

The trends that are shaping the twenty-first-century world embody both promise and peril. Globalization, for example, has lifted hundreds of millions of people out of poverty while contributing to social fragmentation and a massive increase in inequality, not to mention serious environmental damage.

By the time we see that climate change is really bad, your ability to fix it is extremely limited... The carbon gets up there, but the heating effect is delayed. And then the effect of that heat on the species and ecosystem is delayed. That means that even when you turn virtuous, things are actually going to get worse for quite a while.

I have been fighting climate change for two decades, and people often ask me how I remain hopeful in the face of extreme weather and grim forecasts. The answer is simple: I see countless solutions spreading across the nation and across the world. But we need more investment.