Ash Carter, Former US Secretary of Defense

On running the Department of Defense: “It's truly vast and obviously has the most consequential mission, which is why it's so fun and deeply satisfying to be part of because you tend to forget, if you have security, you don’t think about it. And I always used to say, security is like oxygen. When you have it, you don’t think about it. When you don’t have it, it's all you think about. And my job was to protect our country, deter, and if necessary, destroy our enemies, and leave a better world for our children.”

On the US-China relationship: “We have been in a sustained competitive relationship with a Communist dictatorship for decades before. It was called the Soviet Union. But the difference was we didn’t trade with the Soviet Union…. We trade with China. We have abundant, voluminous trade with China. Everybody else trades with China. So you've got to think about this completely differently. And I'm afraid that our policymakers of all kinds, and our economists, for that matter, run around with two models in their head: cold war or free trade. Well, neither of them applies to this circumstance. So we need a new playbook.”