Did I recognize that there was anger or frustration in the American population? Of course I did. First of all, we had to fight back from the worst recession since the Great Depression, and I can guarantee you if your housing values have crashed and you've lost most of your pension and you've lost your job, you're going to be pretty angry.

I've said repeatedly that where we see terrorist organizations like al-Qaeda or ISIL, they have perverted and distorted and tried to claim the mantle of Islam for an excuse, for basically barbarism and death. These are people who kill children, kill Muslims, take sex slaves - there's no religious rationale that would justify in any way any of the things that they do.

All this marked them as vaguely liberal, although their ideas would never congeal into anything like a firm ideology; in this, too, they were American.

So while I will never minimize the costs involved in military action, I am convinced that a failure to act in Libya would have carried a far greater price for America.

I think it's very important to remember that so much of the work that gets done between countries is not done at the level of presidents, but is done within various agencies, whether it's law enforcement or economic ministries. And when they establish relationships and systems of communications and shared projects and shared visions, those structures continue even after any particular president is gone. It builds trust and understanding between countries that are critically important.

This comes from a group of people who`ve been wrong about every foreign policy issue over the last two decades. They supported Hillary Clinton`s war in Libya. They supported President [Barack] Obama`s bombing of Assad.

Part of what's unique about climate change, though, is the nature of some of the opposition to action. It's pretty rare that you'll encounter somebody who says the problem you're trying to solve simply doesn't exist. When President Kennedy set us on a course for the moon, there were a number of people who made a serious case that it wouldn't be worth it; it was going to be too expensive, it was going to be too hard, it would take too long. But nobody ignored the science. I don't remember anybody saying that the moon wasn't there or that it was made of cheese.