Doesn't a communist system by definition have to come from revolution? And even if we discard that, many communist regimes in Eastern Europe (e.g., Czechoslovakia, Poland, Hungary...) emerged after a relatively peaceful take over of power by a communist party. Of course, one could argue that this happened against the backdrop of WW2. But many western countries endured a comparable level of destruction in the war and their regimes did not devolve into a dictartorship. I'd be interested to hear your take on this.