Throughout history, the most powerful countries have often had a hard time finding friends. As a nation grows dominant, others tend to balance against it. Look at Russia’s neighbors in Eastern Europe; countries rushed into NATO the moment the world allowed it. Look at China’s neighborhood in Asia, where Japan, India, Australia, Vietnam and others have steadily tightened their security ties with the United States and each other in response to Beijing’s rise.

But then look at the U.S. - and the theory starts to wobble.

Throughout history, the most powerful countries have often had a hard time finding friends. As a nation grows dominant, others tend to balance against it. Look at Russia’s neighbors in Eastern Europe; countries rushed into NATO the moment the world allowed it. Look at China’s neighborhood in Asia, where Japan, India, Australia, Vietnam and others have steadily tightened their security ties with the United States and each other in response to Beijing’s rise.

But then look at the U.S. – and the theory starts to wobble.

America is the world’s most powerful nation, yet many of the richest and most capable countries do not balance against it – they ally with it. They defer to it on core security questions. They host its forces. They integrate their militaries with its. That is not normal in the long sweep of modern history. It is, in fact, close to unique.

Why? Not because the U.S. is saintly, but because it has often behaved unlike a classic hegemon. For eight decades since World War II, it has........

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