There were three basic factors that brought down the USSR:
- The system exhausted sources for the economic growth. From the late 1970s onward, the economic inputs in the Soviet Union started to surpass the economic outputs. With the drop in oil prices in the 1980s, we ran out of reserves to compensate for the inefficiencies inherent to our centrally-planned model (see the graph below).
- Sharp rise of ethnic nationalism, starting with the Jeltoqsan riots in 1986.
- Military setbacks amid the dramatic escalation of arms race: the Afghan war, Operation Mole Cricket 19, the impossibility to match the increasing technology gap in the latest military technologies. This created an enormous pressure to close the gap, which made the top elite start casting around for new approaches. That’s how the Perestroika and Glasnost weren’t shot down right from the outset.