The whole technological revolution and evolution gives man tremendous capabilities for good, and it also gives individuals tremendous capability to carry out what result in lethal action.

When we uphold the rule of law, our counterterrorism tools are more likely to withstand the scrutiny of our courts, our allies, and the American people.

I will not, nor will I ever, publicly divulge sensitive intelligence sources and methods. For when that happens, our national security is endangered and lives can be lost.

You always, I think, debate with yourself about whether or not you made the right decision. And you have to then give the person that you’re working for - in my instance, the president - your best judgment based on your understanding of the facts, but also the calculus you use to make a determination about what’s the best way to go forward.

I go to bed at night worrying that I didn't do enough that day to make sure I protect the American people.

How you define a problem shapes how you address it.

The risk of just one terrorist with just one nuclear weapon is a risk we simply cannot afford to take.