This ceased to be true with the collapse of the Soviet Union. Suddenly the U.S. was the only power standing. It was the “unipolar moment” — one that could and should be extended indefinitely. Now America defined its interests in breathtakingly broad terms. Our military didn’t just need to defend our borders (which, with Canada and Mexico as neighbors, was simple, easy, and cheap). It needed to “spread democracy,” not just as a check on a rival geopolitical system (as was the case from the mid-1940s to the late ’80s) but in absolute terms: the more democracy, and the more markets, the better. Everywhere. Just as any sign of resistance to democracy and markets anywhere in the world looked like a threat. Other countries could rise economically, but only if they refrained from challenging the military, political, and economic primacy of the United States.
Now the U.S. was not only the world’s policeman. It increasingly saw itself as international justice’s judge, jury, and executioner and the self-appointed guarantor of world order. Just as a government rightly views challenges by private citizens to its monopoly on violence as a threat to its power and legitimacy, so the U.S. now treated any form of resistance to the “liberal international order” as a direct threat to its rule. America had becoming incredibly powerful — the most powerful nation in the history of the world — but our very inability to control every corner of that world served as evidence that we needed to become more powerful still.