IMHO insufficient credit has been given to Afghanistan in the demise of the Soviet Union. I think the devastating impact on both the economy and the Red Army influenced the decisions not to respond with force in Poland and Lithuania when they began to break away. I don’t buy Gorby’s line that he didn’t do it because he was just a closet liberal social democrat all along.
To this day, Gorbachev doesn’t want to admit that he was pushed around from inside and outside the country.