If you don't understand what al Qaeda was trying to do on 9/11, if you don't have a sense of who Osama bin Laden is as a person, if you don't have a sense of what al Qaeda, the organization, was on 9/11, 9/11 appears to be more or less inexplicable.

Why should Americans care about the Nazi back story in World War II? If you don't have the Nazi back story in World War II, World War II is simply not comprehensible.

At one point people in al Qaeda were actually drawing monthly paychecks when they were based in Sudan.

Bin Laden was 200 miles away from the area where all of these drone strikes were taking out his key leaders in al-Qaida. He was able to indulge in his hobbies... He was making occasional video tapes and audio tapes for release to the wider world.

Bin Laden's death is just a punctuation point on a set of problems they've had for a long time. I think the prognosis for al-Qaida and groups like it is really bad, and that's a good thing.

I've interviewed multiple people who know bin Laden... who tend to have a universal picture of what he's like, which is: modest, retiring, unassuming, kind of thoughtful - lots of things that don't fit with a mass murderer, which he is as well.

The terrorists who have succeeded in carrying out spectacular attacks against Western targets in the past have been college-educated, technically proficient men who are capable of manufacturing and deploying chemical, radiological, and biological weapons. Al Qaeda attracts the kind of highly educated men who one day might be able to pull off such an attack.