I had no difficulty as Secretary of Defense moving from the Bush administration to the Obama administration.

I think in the context of senior government positions, I think an anecdote of what I told President-Elect Barack Obama when we had our first meeting. And I said, "You don't know me. Can you trust me? Why do you think you can trust me?" and so on. But at the end, I said, "You can count on me to be loyal to you. I will not leak. I will keep my disagreements with you private. And if I cannot be loyal, I'll leave." Loyalty means doing what you think is in the best interest of that person as well as the country.

I didn't think this whole business with Director James Comey was handled well. So there are sort of day-to-day aspects of the operation that I think are really troublesome. And I know that there are a lot of people in the country who have lots of issues with decisions that Donald Trump has making on the domestic side.

In government, I'm a strong believer in the need for reform of government agencies and departments. They - they have gotten fat and sloppy, and they're not user friendly. They are inefficient. They cost too much.

I will always be an advocate in terms of wars of necessity. I am just much more cautious on wars of choice.

It's clear the relationship between China and North Korea has hardly ever been worse. Kim Jong-un has never been to Beijing in his leadership. The Chinese press are saying some amazingly negative things about the north, and about Kim Jong-un. So - so they are weighing in, and they are bringing greater pressure. Whether it will be enough I think remains to be seen.

When I was the director of Central Intelligence in the early '90s, I tried to get the Air Force to partner with us in building drones. And they didn't want to, because they had no pilots.