With President Bush's go-it-alone policy foundering in Iraq, many of his critics are calling for a return of American foreign policy to a traditional multilateralism centered on the United Nations. Bush's critics are right to point out that the United States benefits when its actions enjoy U.N. blessing. Gaining such support can often be as important as demonstrating America's power and will to act. But they fail to acknowledge publicly what everyone admits privately: that as a pre-Cold War institution operating in a post-Cold War world, the United Nations is not up to the task of handling the most pressing...