The Soviet Union, officially known as the Union of Soviet Socialist Republics, was a union of countries in northern
Eurasia. It was governed as a single-party state that existed between 1922 and 1991, ruled by the Communist Party with Moscow as its capital.
During the Cold War, it was the United States' principal adversary and rival. Dr. Manhattan played a crucial role in maintaining deterrence so that a deadly conflict would not break out between the countries. When Dr. Manhattan left for Mars in October 1985, deterrence breaks down, and the Soviet Union, emboldened, invades Afghanistan (something which happened in our world in 1979). A global nuclear war looms which is only averted when the contending powers come to believe that the Earth is threatened by aliens, thanks to Ozymandias's ambitious hoax. By the end of Watchmen, an accord between the United States and the Soviet Union has considerably reduced tensions and created hopes for a wave of lasting peace. Rorschach's journal, if published and believed, would threaten the accord and perhaps lead to renewed hostilities.