The Soviet Union collapsed due to a combination of multiple interrelated factors including economic crisis, political paralysis, nationalist movements, and the effects of reforms by Mikhail Gorbachev. The economy was burdened by heavy military spending, inefficient central planning, stagnation, and costly military engagements like the Afghanistan war. Politically, the system was authoritarian and bureaucratic with little democracy, and Gorbachev's policies of glasnost (openness) and perestroika (restructuring) loosened the state's control but unintentionally destabilized the regime. Nationalist movements within the diverse republics pushed for autonomy and independence, further fragmenting the union. The loss of central government control, especially through Russia's push for power and eventual independence, led to the disintegration of the USSR into independent states by 1991. External factors such as competition with the U.S., the arms race, and diplomatic isolation also contributed to weakening the Soviet system.