I was alive 20 years ago when Russia (the Soviet Union) let 14 Republicans go. I have no trouble imagining them letting territory go.
Which Republicans did they have captured? It was generous to let them go. On a serious note, the USSR was flat broke when the Iron Curtain fell. Russia could not have held onto those countries it if were threatening to use their nukes. The lack of Russian money was one of them main reasons why North Korea went through horrible starvation. It's why the DDR had rampant runaway inflation until they were absorbed back into Germany.