My mistake, my history must be off because I could swear that Serbia was Yugoslavia which I thought had a puppet government put there by Russia.
SFR Yugoslavia had 6 member states. Yes, one of them was Serbia as its backbone.
But, Yugoslavia was strong and independent, not under anyone's control. Josip broz Tito was a dictator in this state and he was a "G-d" in this society. Soviet Union wanted to establish its control, but Tito refused, so it was an independent state ruled by communist dictator Tito with its own kind of socialism, as a mix of planned and market economy. It was the richest socialist state in the world.
You should watch a movie called "The Weight of Chains" by Boris Malagurski. Everything is explained here and it is very interesting documentary, not boring. I think you will like it.
You can watch full movie here>
http://www.movie2k.to/The-Weight-of-Chains-watch-movie-675439.html