The United States dominates the world as no state has. It emerged from the Cold War the world's only superpower, and no geopolitical or ideological contenders are in sight. Europe is drawn inward and Japan is stagnant. A half-century after their occupation, the United States still provides security and garrisons troops in Japan and Germany – the world's second and third largest economies. US military bases and carrier battle groups ring the world. Russia is in a quasi-formal security partnership with the United States, and China has accommodated itself to US dominance, at least for the moment. For the first time in the modern era, the world's most powerful state can operate on the global stage without the counterbalancing constraints of other great powers. We have entered the American unipolar age.