Six factors responsible for the disintegration of USSR are:
1. The internal weaknesses of Soviet political and economic institutions failed to meet the aspirations of the people.
2. Economic stagnation for many years led to severe consumer shortages and a large section of Soviet society began to doubt and question the system and to do so openly.
3. The Soviet Union had become stagnant in an administrative and political sense as well. The Communist Party that had ruled the Soviet Union for over 70 years was not accountable to the people. Ordinary people were alienated by slow and stifling administration, rampant corruption, the inability of the system to correct mistakes it had made, the unwillingness to allow more openness in government and the centralisation of authority in a vast land.
4. The Soviet economy used much of its resources in maintaining a nuclear and military arsenal and the development of its satellite states in Eastern Europe and within the Soviet system. This led a huge economic burden that the system could not cope with,
5. When Gorbachev became the President, he carried out reforms and loosened the system. He set in motion forces and expectations that few could have predicted and became virtually impossible to control. There were sections of Soviet society which felt that Gorbachev should have moved much faster and were disappointed and impatient with his methods. Others, especially members of the Communist Party and those who were served by the system, took exactly the opposite view. In this tug of war, Gorbachev lost support on all sides.
6. The rise of nationalism and the desire for sovereignty within various republics including Russia and the Baltic Republics, Ukraine, Georgia, and others proved to be the final and most immediate cause for the disintegration of the USSR.