On August 16, 1991, Soviet President Mikhail Gorbachev was placed under house arrest during a coup attempt by high-ranking officials opposed to his reform policies. The coup ultimately failed, resulting in the collapse of the coup plotters' leadership and contributing to the dissolution of the Soviet Union.

Coup d'etat : it's French for taking of the state, overthrow, etc.

Coup d'etat has three syllables: coup-d'e-tat

When the Soviet Union fell apart, the Commonwealth of Independent States was created in an attempt to replace the Soviet state. It was established in 1991.