Agreed. When the Soviet Union existed, everyone talked about how Poland, East Germany, Czechoslavakia, etc. were its buffer states. They were kept dependent on the USSR and served as its first line of defense. That's the same thing in North Korea. It's impossible to believe that China (or really, its dictators who only want to keep themselves in their privileged positions) could care so much about controlling its people and keeping a claim on Taiwan, but are hands off Korea.