The Long Peace is a term for the historical period following World War II. This period of Cold War was marked by the absence of major wars between the great powers of the period, the USA and the USSR. It is speculated that the obvious political errors leading to World War I and World War II with their subsequent horrors and, thereafter, the acquisition of thermonuclear weapons by the opposing powers of the United States and the Soviet Union exerted a restraining influence on the leaderships of the major powers. Following the collapse of the Soviet Union in 1991 and the rise of China as a major power, there followed two decades of continued absence of direct conflict between major states, though lesser military conflicts occurred. A phrase meant to express the length of the peace in Europe