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.

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

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

[General James Mattis] a very talented individual. He's - has a personal library of about 10,000 books and he's read most of them on military history and strategy and so forth.

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.

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.

t I think what [James Mattis] will do with the deal is monitor it very, very carefully and make sure that Iran is complying with every stipulation of it.