The overwhelming reality of our time is this: In the opening years of the 21st century, the United States finds itself not only the most powerful nation on earth but the most powerful nation that has ever existed. Given the contradictory roles America plays in the world, we are fated to be the catalyst for either a new global community or for global chaos. If we don't lead, Zbigniew Brzezinski contends, rather than merely dominate by force, we could...