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.

The absence of a focal enemy, which is what the Cold War had provided; the complexity of the developments that are occurring that mean that the world is just extremely complicated - lots of different and competing stories and strands; the continuing reality of megaterrorism; and the dysfunctionality of our politics that has neglected the foundations of the U.S. role in the world; have altogether left us somewhat confused.

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?

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

There are two great tragedies in life: one is to fail to achieve one's grandest ambitions, and the other one is to succeed.

Putin needs to understand and feel in his gut that if the Chechens get a nuclear bomb, they're going to Moscow first, they're not coming to New York.

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.