Re-examining our reasoning is not something that has come naturally to American statesmen.

Without investing in the rule of law for the poor, none of the other investments we make will be sustainable.

There's something beautiful about working in the one place in the world where the world is present, like United Nations. Otherwise, one would have to go to each of these countries to negotiate.

I think that the only time we will really know what then-President Trump is going to do about the set of challenges that confront him is after he has sat down with his advisers as the commander in chief, when he's looking at the threats and the intelligence from the standpoint of being the number one decider, when he's hearing from his secretary of defense, his chairman, who was the same chairman President Obama had, Chairman Joe Dunford, who is an outstanding public servant, who has led our anti-ISIL effort, on which we're making great progress.

Foreign policy is an explicitly amoral enterprise.

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.

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.