Yeah, I don't think Vietnam counts as any sort of occupation. It is an instance of a war of aggression by China though. I do consider it to be a mistake on the part of Chinese leadership, but the reality is that every society makes mistakes. Societies run by communists aren't immune from that, and that's just life.

In my view, the question is always how these societies compare to other real world alternatives. Even if we take the most critical view of China in cases of Vietnam, it's clear that there is no comparison with the US. The path of development China took is overwhelmingly peaceful, and one that helped improved life both in China and in many other nations around the world.