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.

Terrorism is really the only existential threat to America as we know it - as a free country that plays a leading role in the world.

When we succeeded in winning the Cold War, escaping a nuclear Armageddon that could have killed us all, the U.S. inevitably had a serious problem about an encore: what now for our place in the world?

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.

One of the three big factors that count against war in the relationship between China and the U.S. are, first, nuclear weapons and even a condition of mutual assured destruction. Secondly, one's got two economies that have become so deeply interlaced that a war between the U.S. and China would leave Wal-Marts empty and Chinese factories producing for nothing. Thirdly, climate - if between the two of us, we keep doing what we're doing, we can create a climate in which our grandchildren won't be able to live.

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.