A world government would reduce the probability of a catastrophic nuclear world war  Ever since the destruction of the Japanese cities of Hiroshima and Nagasaki in 1945 during the closing days of World War II, the threat of global devastation through nuclear world war has hung over human civilization like a Damocles’ sword. The threat of global nuclear destruction peaked during the most perilous years of the Cold War during the 1950s through the 1970s, and it gradually subsided thereafter. With the collapse of the Soviet Union in the early 1990s, many people came to believe that the threat has entirely disappeared. But this is false complacency. Although national arsenals of nuclear-tipped ICBMs have declined in the two decades since the end of the Cold War, they still exist at levels that would cause unimaginable death and destruction were they unleashed in a world war. The history of human civilization throughout the ages demonstrates the strong propensity among human beings toward hostility, violence and warfare—whatever the potential cost. As long as the international political system is based upon the sovereignty of nation-states, the threat of nuclear world war will always be there.