I think one has to say it's not just simply a matter of capturing people and holding them accountable, but removing the sanctuaries, removing the support systems...

Putin is behaving in a very dangerous way. And Donald Trump sounds as though he would simply sit back and allow that to go on. I worry about where that would end up.

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

It would be a huge mistake to abandon democracy promotion. Peaceful political change has been enormously successful in the past years in Eastern European countries as well as in countries like South Korea, South Africa, Chile and Indonesia. However, if possible, the use of force is something to avoid except in cases where genocide is threatened, like Bosnia or Libya or with regimes that threaten our security, like the Taliban and Saddam Hussein.

Islamic State is mainly a direct result of the failure in Syria. That's where IS has grown. That's where IS spread from.

People seem to forget that Saddam was the only leader in the world who praised the attacks of 9/11 as a good thing.

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