Answer:
Economic downfall, political upheaval
Step-by-step explanation:
Policy reform by Gorbachev who was the then Secretary General of the Communist party in 1985 saw a promotion of a policy called of Openness(Glasnost) and restructuring (perestroika); these policy created room for a critism and democratic uprising- there was lost of government control of the media in the process.
The war with Afghanistan which met a stalement with opposition from the US supporting the Afghans also brought about a weakening of their army.
In terms of Economic the economic system dwindled interms of fall of oil price from $120 to about $20; the USSR was reckoned as a major exporter of oil and gas then. This did not bring about sudden collapse but contributed. The well funding of the military in an unrational fashion of a dwindling economic promulgated by not well apportioning resources to empower would be entrepreneurs and small scale business also climatised to the fall of USSR.