The collapse of the Soviet Union refers to the disintegration of the political and economic structure of the USSR, which officially occurred on December 26, 1991. This event marked the end of the Cold War and led to the emergence of 15 independent republics, fundamentally altering the geopolitical landscape of Europe and beyond. The collapse was largely driven by internal issues within the Soviet state, including economic stagnation, political corruption, and rising nationalist movements, alongside the reform agenda introduced by Gorbachev.