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

Most governments lie to each other. That's the way business gets done.

I think Donald Trump has gotten China's attention to a degree that his predecessors have not that this is a very serious matter for the United States.

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

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.

Congress is best viewed from a distance - the farther the better - because up close, it is truly ugly.

If there's ever an example that military power alone cannot be successful in Afghanistan, I think it was the Soviet experience.