I know there are fifteen officially recognized post-Soviet states, but there were other nations which were considered part of the Eastern Bloc that weren't formally considered part of the Union.
Romania was a member of the Warsaw Pact, but never a Soviet Republic. IIRC they actually fought against Russia(w/Germany) in WWII. They were never one of the stronger, more aggressive members of the Warsaw Pact. They didn't participate in the invasion of the Czechs.
@hlpflwthat Romania and Hungary were both occupied by Nazi Germany during WWII and very reluctantly fought the Russians, although with minimal effect because they hated the Nazis as much as anyone.