People change their habits. I know Americans who don't go to Paris because they think it is too dangerous.

One of the things that ultimately led me to leave mathematics and go into political science was thinking I could prevent nuclear war.

NATO is still the most remarkable alliance in history. It stuck together through 40 years of Cold War, and it then joined together to fight in Afghanistan. In the 1980s, I would not have thought this was going to be possible.

It's hard to conceive that it would take more forces to provide stability in post-Saddam Iraq than it would take to conduct the war itself and secure the surrender of Saddam's security forces and his army. Hard to imagine.

The most striking thing is that even before Osama bin Laden was killed, he seemed largely irrelevant to the Arab Spring.

It's a very bad thing when people exterminate other people, and people persecute minorities.

I don't know of a single instance of these Arab freedom fighters holding up pictures of bin Laden. I know many instances of them displaying American flags in Benghazi or painting 'Facebook' on their foreheads in Cairo. The idea of freedom . . . is absolutely contradictory to what bin Laden stood for, which was . . . taking Muslims back to some medieval theocracy and encouraging people to die not for freedom but to go to paradise and to kill innocent people along the way. The contrast is really striking.