The primary cause of the dissolution of the Soviet Union in 1991 was a combination of economic stagnation, political corruption, and rising nationalist movements among its republics. The centrally planned economy faced severe inefficiencies, leading to shortages and dissatisfaction among citizens. Mikhail Gorbachev's reforms, including perestroika (economic restructuring) and glasnost (political openness), aimed to revitalize the system but ultimately weakened the Communist Party's control. Nationalist sentiments surged, particularly in the Baltic states and Eastern Europe, as republics sought independence. This culminated in a failed coup in August 1991 and the eventual formal dissolution of the Soviet Union on December 26, 1991, resulting in the emergence of independent states.