Dissolution of the Soviet Union

The Soviet Union was dissolved on December 26, 1991. On the previous day, Soviet President Mikhail Gorbachev, the eighth and final leader of the Soviet Union, resigned, declared his office extinct, and handed over its powers – including control of the Soviet nuclear missile launching codes – to Russia President Boris Yeltsin.

Behind the curtains, the Dissolution of the Soviet Union, was according to the Templar Order's will, who dominated the nation since the Stalin's era.

Reference

 * Assassin's Creed II – Glyphs