Constraint theory argues a number of things. First, that the impossible has to be identified. Second, that the actor is then constrained by circumstances to act a certain way. For example, should we invade ISIS? Can we invade ISIS? What would it take to invade ISIS? Once you ask that question you discover the price of that option and then you take a look at American politics and see that the country is probably not prepared to invest the 2 to 3 million people that it would take to defeat ISIS and the insurgency afterwards. All right, so that's not going to happen.

But every time new powers emerge they have to find their balance. New powers are emerging, old powers are declining. It's not that process that's dangerous, it's the emerging position that's dangerous.

While certain coastal cities have become very prosperous, the rest of China has a per capita income of $200 a year. The coast wants to have nothing to do with the interior; it wants to work with Tokyo and New York. This is an old story in China. It is why Mao succeeded in 1927. He wanted [coastal] Shanghai to throw the foreigners out, but Shanghai was doing too well financially [to expel foreigners]. So Mao went to the interior and raised a peasant army. He came back to Shanghai and sealed off the country.

Politicians are enormously smart and rational. They don't have the same interests as businessmen ... But a man rises to the top of the United States. He's clawed his way out of 330 million people. OK. He didn't do that because he was dumb, or lucky, or something like that. He understands power. And he understands how to take it. And he understands how to keep it.

What is American strategy first of all? So American strategy is to command the seas, right? The foundation of our power is sea control. Nobody can invade us, but we can invade them.

There is no difference in a country between military, economic, and political affairs. It's useful for Business Insider to divide things that way. That's useful for a college program. But a country is a country. How do you understand China's economy without China's army? If you take these all into account you're ready to explain a question like, "How come the US doesn't have a debt problem?"

There is a radical and unprecedented shift [in war] that is part of the general transformation of civilization. First, understand that the past 150 years of warfare are totally unprecedented in that we introduced a breathtakingly inefficient technology: guns. In the First World War, and this is not an exaggeration, it took 10,000 rounds of ammunition to kill one person. Any given shot had a one in 10,000 probability of ending someone's life.