The collapse of the Soviet Union refers to the disintegration of the political and economic system of the USSR in 1991, resulting in the emergence of 15 independent republics and a significant shift in global geopolitics. This event marked the end of the Cold War era, drastically altering U.S.-Russia relations and affecting international alliances and conflicts. The dissolution was driven by various factors, including economic stagnation, nationalist movements within the republics, and political reforms initiated by Mikhail Gorbachev.