A Unipolar World Americans have an healthy aversion to foreign policy. It stems from a sense of thrift: Who needs it? We’re protected by two great oceans, we have this continent practically to ourselves and we share it with just two neighbors, both friendly, one so friendly that its people seem intent upon moving in with us. It took three giants of the twentieth century to drag us into its great battles: Wilson into World War I, Roosevelt into World War II, Truman into the Cold War. And then it ended with one of the great anti-climaxes in history. Without...