Today the United States stands alone as the world's only superpower. This stature became possible only after the sharp decline of the Soviet Union during the watershed years of 1989 to 1991. The ultimate victory of the United States in the Cold War, a rivalry that had begun in 1946, confirmed to many Americans the superiority of their national virtues and resources and validated their nation's worthiness to lead the world. The expression American triumphalism refers to two related subjects pertaining to the global supremacy America has achieved. In the narrower sense of the term, triumphalism refers to the role the United States played in defeating its Cold War rival by forcing the Soviet Union to pursue various policies that culminated in the Soviet system's collapse. The second, broader meaning of triumphalism conveys the sense that the United States enjoys its current power and leadership role because it possesses qualities and...