No other power or constellation of powers is able to provide even a fraction of the global order provided by the United States. U.S. air and sea dominance preserves the peace, such as it exists, in Asia and the Greater Middle East. American military force, reasonably deployed, is what ultimately protects democracies as diverse as Poland, Israel, and Taiwan from being overrun by enemies. If America sharply retrenched its air and sea forces, while starving its land forces of adequate supplies and training, the world would be a far more anarchic place, with adverse repercussions for the American homeland.
Rome, Parthia, and Hapsburg Austria were great precisely because they gave significant parts of the world a modicum of imperial order that they would not otherwise have enjoyed. America must presently do likewise, particularly in East Asia, the geographic heartland of the world economy and the home of American treaty allies.
This by no means obliges the American military to repair complex and populous Islamic countries that lack critical components of civil society. America must roam the world with its ships and planes, but be very wary of where it gets involved on the ground. And it must initiate military hostilities only when an overwhelming national interest is threatened. Otherwise, it should limit its involvement to economic inducements and robust diplomacy—diplomacy that exerts every possible pressure in order to prevent widespread atrocities in parts of the world, such as central Africa, that are not, in the orthodox sense, strategic.