When it came to the Vietnam War, Mr. McNamara was an early advocate of escalation but came to realize the flaws in the American approach earlier than many of his colleagues. Yet in public, he continued to defend the war.

My second epiphany came as an intern at the Carnegie Endowment for International Peace. The man I worked for was consumed with what was going on in Bosnia. And the more I knew [about it] the more saddened I was. There were these images of emaciated men behind barbed wire.... It was like, I've got to find a way to do something.

The story of U.S. policy during the genocide in Rwanda is not a story of willful complicity with evil. U.S. officials did not sit around and conspire to allow genocide to happen.

I was working in the same building as U.S. News & World Report, and I banged on the door and said, "I'm ready to go." And they said, "What's your combat experience?" I said, "Does my parents' divorce count? It was pretty rough." Then they said, "What's your reporting experience?" And I said, "I covered the women's volleyball team in college exceptionally well." The guy was like, "You are so not ready to be a war correspondent."

I joke that I spent 38 years scouring the globe, going to war zones, trying to find the person with my exact birthday.

It is easy to get used to the morning news, habituated. But don't. The morning news is yours to alter.

One of the things that a president needs in the face of genocide is resolve.