It was Mikhail Gorbachev, the Communist Party Secretary who promoted the policies of “perestroika” (reconstruction) and “glasnost” (openness) to reform the distraught Soviet Union.
These policies were in effect from 1985 to 1991, when Boris Yeltsin became Russia’s first popularly elected president. He then formed the Commonwealth of Independent States.
As per Coldwar.org, reconstructing the organization of the Soviet Union proved difficult and the effects were mixed; while more social freedoms were permitted, the economy was in deterioration and social unrest was growing among the people. Glasnost and Perestroika eventually helped cause the fall of the Soviet Union and the end of the Cold War, which had lasted from 1945 to 1991.
Learn more about Mikhail Gorbachev by checking his biography told through text and video clips at BBC History.