Quote Originally Posted by woad&fangs
Because Tibet never should have been part of China to start with. If France invaded Belgium and 50 million* Frenchmen moved into Belgium would France not be forced to give Belgium its independence back?

*note that I'm completely ignorant of the population of Belgium.
Both versions of the Chinese republic claimed Tibet as part of their inheritance from Qing China, neither having given it up through right of war or treaty. The Republic of China (ROC, nowadays Taiwan) claimed Tibet as part of Chinese territory, but did not have the muscle to back this claim before they were expelled from the mainland altogether. The People's Republic of China (PRC) continued this claim, and they did have the muscle to back this claim, which they did soon after their succession. The legal comparison one should look at is not an invasion of Belgium, but of Hong Kong. Hong Kong (strictly speaking, the New Territories) and other concessions were ceded by treaty by Qing China, treaties which both the ROC amd the PRC decried as unfair. But both Chinas observed these treaties, for they were part of their inheritance, and a proper successor state observes the treaties signed by its predecessors.

So Tibet is legally part of China, unless someone wishes to force Beijing into giving its independence. If one is concerned about what China is doing there, the issue is not one of a foreign invader oppressing a conquered territory (it's as much part of China as Virginia is part of the US), but whether human rights override sovereign rights. But as sovereign rights depend on the state's ability to keep itself together and free from outside influence (what the monopoly on organised violence is meant to achieve), so human rights depend on the state's willingness to observe them. If a state wishes to assert sovereign rights over human rights, what right, or more relevantly, what power does an outsider have to prevent this?