China had a sadistic crazy butchering ally, they've failed to keep that ally regime from being toppled by Vietnam, China has invaded Vietnam but was met by stiff resistance and had to retreat (which looks much more like a defeat rather a draw, especially given the difference in size between parties) and of course China no longer had the Cambodia - Vietnam did not occupy it either but I'm not sure they seriously planned to.

I'm really weak in that kind of history so I may get everything off, but that's what it looks from the outside.