Development is a lot cheaper than sending soldiers.

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.

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

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

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 mean, when you get down to very low numbers of nuclear weapons, and you contemplate going to zero, how do you deal with the reality of that technology being available to almost any country that seeks to pursue it? And what conditions do you put in place?