It's Soviet, it isn't misleading but the correct phrasing would be that it's the only remaining Soviet country in Europe, the problem is people think Soviet literally always means "of the Soviet Union," not knowing Soviets are a type of legislative branch, so communist is a pretty good approximate if you know communist doesn't literally mean Stalinist... yeah, there's no way of making it clear to the average person without making the sentence boring or overly-detailed.