Why do soldiers fight? They join because they believe in a higher cause -- protecting religion, their nation, defending against a foreign nation. But why do soldier stay and fight? Soldiers aren't individuals. They are part of a unit. And that unit is led by a commander. If they don't trust their commander ... if there is no leadership, there is nothing.

[General James Mattis] said, reading allows you to learn from other people's mistakes without filling body bags with the bodies of your soldiers as you learn on the battlefield.

Michele Flournoy, by the way, is not just a talented and bright person. She was Hillary Clinton's secretary of defense in-waiting. So for her to give General [James] Mattis her support, that says something significant.

So in his very politically-incorrect way, I think [James Mattis] is a good counterpart to Donald Trump, who doesn't read books.

Given this president [Donald Trump] and his lack of military experience, I think it actually might be a good thing to have someone who understands the military very deeply to be counseling him.

Certainly, we shouldn't go about making a habit of taking generals and making them secretary of defense.

Iran has proxies in Yemen, Syria, Iraq. You can push back against Iran without pulling out of the deal.