The fact that there are now many entities that may have some loose affiliation with a former core Al Qaeda - or who have decided to fashion themselves as an affiliate or follower in the Al Qaeda jihadist tradition - as well as groups that are just inspired by the concept that they could also be the perpetrators of mass killing, means that there is a spectrum of threats.

I think the election of Trump was an expression of what happens in ruling powers as they become alarmed.

For interests that are vital to the U.S. - that is, essential for our survival and wellbeing - the U.S. should be prepared to use military force - including unilaterally, if necessary.

If the Britain and France had done what they were obliged to do under the treaty and sent troops to enforce the treaty when Hitler remilitarized the Rhineland, the German general staff would have turned Hitler out. And one would not have had a cause for war, and you wouldn't have had World War II.

The best simpleminded test of expertise in a particular area is an ability to win money in a series of bets on future occurrences in that area.

And I hope that we can learn the lessons of the past in looking at the current challenge that China poses to a ruling America.

Given that the Al Qaeda core has been significantly destroyed or disabled, and that the leadership seems to be essentially on the run or in hiding, it would lead me to think that probably it is one of the less centralized groups that might be the greatest danger.