What broke up after President Gorbachev's resignation in 1991?

The Soviet Union broke up after President Mikhail Gorbachev resigned in 1991. His resignation was the final, highly visible moment in the dissolution of the Union of Soviet Socialist Republics, commonly called the USSR.

The breakup followed years of economic stagnation, political reform and growing nationalist movements in the Soviet republics. Gorbachev's policies of glasnost, or greater openness, and perestroika, or restructuring, loosened central control but also exposed deep conflicts within the multinational state. A failed hard-line coup in August 1991 further weakened the Union government and strengthened Russian leader Boris Yeltsin.

On December 8, 1991, Russia, Ukraine and Belarus signed the Belovezha Accords, declaring that the Soviet Union had ceased to exist and creating the Commonwealth of Independent States. Other republics soon joined the agreement. Gorbachev resigned as Soviet president on December 25 and transferred his powers to Yeltsin.

The legal dissolution was completed on December 26, when the Soviet of the Republics formally declared the Union dissolved. The event left 15 independent former Soviet republics and is widely regarded as marking the end of the Cold War era.