On December 25, 1991, the president of the Union of Soviet Socialist Republics (USSR), Mikhail Gorbachev, resigned, leaving Boris Yeltsin as president of the newly independent Russia. As the world watched in amazement, the most successful communist country, the USSR, collapsed and disintegrated into fifteen separate countries. Though some expert argue that the Soievt's "experiment" of Communist ideology was doomed to fail from the start, it seems that the dissolution of USSR was radical and unexpected. In actuality, the collapse was a sensible result that was triggered by multiple events. The collapse of USSR was a result of both internal and external forces. It was a reaction of radical economic changes, a wish of independence of Union States, and a struggle between political leaders and international pressure. .
Economy stagnation was one of the reasons that caused the collapse. In the 1980s, after several years of economy growth, USSR struggled in an economic stagnation which was considered as an inevitable result of a long-term command economy. First, an increase of pension burdened the USSR. Michael McFaul and Stoner-Weiss Kathryn reported that "Soviet population growth dropped about 50 percent between 1960 and 1980, causing a decline in the size of the workforce and in the increase in pensioners in need of state support." The pension was not the only economic pitfall of the union. After World War II, people increasingly sought for a much variety of goods which should not only fill their basic needs, but also satisfy their personal demands. However, the command economy, which the USSR had practiced for years, was not designed for the much complex modern economy. As the demands of people increased significantly, the industrial supplies fell behind. The outmode planning system was unable to hold the economy, and therefore caused the stagnation (McFaul and Stoner-Weiss).