One answer, I suspect, is that like all too many Americans, Trump has a hard time grasping the fact that other countries are real — that is, that we’re not the only country whose citizens would rather pay a heavy price, in money and even in blood, than make what they see as humiliating concessions.

Ask yourself, how would Americans have reacted if a foreign power had assassinated Dick Cheney, claiming that he had the blood of hundreds of thousands of Iraqis on his hands? Don’t answer that Suleimani was worse. That’s beside the point. The point is that we don’t accept the right of foreign governments to kill our officials. Why imagine that other countries are different?

Of course, we have many people in the diplomatic corps with a deep knowledge of other nations and their motivations, who understand the limits of intimidation. But anyone with that kind of understanding has been excluded from Trump’s inner circle.

Now, it’s true that for many years America did have a special leadership position, one that sometimes involved playing a role in reshaping other countries’ political systems. But here’s where Trump’s second error comes in: He has never shown any sign of understanding why America used to be special.

Part of the explanation, of course, was raw economic and military power: America used to be just much bigger than everyone else. That is, however, no longer true. For example, by some key measures China’s economy is significantly bigger than that of the United States.

Even more important, however, was the fact that America was something more than a big country throwing its weight around. We always stood for something larger.

That doesn’t mean that we were always a force for good; America did many terrible things during its reign as global hegemon. But we clearly stood for global rule of law, for a system that imposed common rules on everyone, ourselves included. The United States may have been the dominant partner in alliances like NATO and bodies like the World Trade Organization, but we always tried to behave as no more than first among equals.