The United States must figure out how to craft for itself a new kind of diplomacy, one that reflects not the country it was in the post-war era but the country it actually is: rich, aging, eager for comfort and luxury, disinclined to fight. Americans, being prideful, naturally bristle at anything that sounds like a tribute payment or protection money, but if you have a great deal of money and no willingness to fight, you had better be honest with yourself about what that means. If we are still a superpower at all, our superpower is money.
An empire is different from a nation in that the supreme imperial power presides over peoples who are fundamentally dissimilar, peoples who are connected not by love or shared aspirations but by commercial and political relationships. Empires are unstable because the corporate aspirations of their constituent peoples are not only different from one another but incompatible with one another — the people in New Delhi and Calcutta could be part of the British Empire or part of the Republic of India, not both. The United States is not an ordinary empire in the sense of the old British Raj, but Washington is the home of an overarching state comprising two great peoples, each of which increasingly sees itself as having interests that are — at best — separate from the other, whose interests, mode of life, and ambitions are at least alien, if not hostile.
These two peoples, being mutually antagonistic at home, find it increasingly difficult to pursue a shared agenda abroad, hence such risible half-measures as the “diplomatic boycott” of the Beijing Olympics.