The twentieth century has been called the American Century. The reason is, of course, the US position as the major superpower in the more than fi fty years after the end of the Second World War, for a long time seriously challenged by the Soviet Union, but at the beginning of the twentyfi rst century the sole superpower, with military, political and economic resources that never existed before for a single state. In the time of the cold war, the United States was the uncontested leader of the coalition opposing Soviet expansion, with the North Atlantic Treaty Organization (NATO) as the main military instrument. It was also the leading economy, using its supremacy in an intelligent way, instrumental in rebuilding war devastated Western Europe through the Marshall Plan (1948), and paving the way for European economic cooperation.