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.

Future U.S. political leaders – those for whom the Cold War was not the formative experience that it was for me – may not consider the return on America’s investment in NATO worth the cost.

I think when it comes to the issues, I'd advise him to stick to the script. But, I mean, Donald Trump is going to have some very tough conversations and he's going to be talking about some very tough and complicated issues in all of the places that he visits.I think anytime a president does things that are humanizing, I think it's - it's good.

In my opinion, any future defense secretary who advises the president to again send a big American land army into Asia or into the Middle East or Africa should 'have his head examined,' as General MacArthur so delicately put it.

The United States has been a global power since late in the 19th century.

On the foreign policy side, there's the risk of being too spontaneous and too disruptive where you end up doing more harm than damage. And figuring out that balance is where having strong people around you matters.

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.