T he United States is the most powerful state in world history–unrivaled in its military, economic, technological, and geopolitical capabilities. Yet America’s authority, measured in terms of credibility, respect, and the ready cooperation of governments around the world, has declined sharply in recent years. In the aftermath of the Cold War, the world seemed to be going in America’s direction. America’s vision of international aspirations was remarkably congruent with the rest of the world’s, a vision symbolized by the fall of the Berlin Wall and the triumph of the ideals championed by the United States: liberal democracy, global markets, and multilateral governance. But today, America and the world are increasingly at odds. In a recent survey of Western European public opinion, the United States was rated as a greater threat to global stability than Iran or North Korea. The United States is positioned at the center of the global system–and its power is unrivaled–but its role as a global leader has never been more controversial, contested, or resisted.