> How does that make it a "necessity"? It's not for China to decide? This is the reasoning Russia uses when invading neighboring countries. To "protect" russian people and claim that <insert part of country> are russians anyway and want to get annexed (still wouldn't make it right). If someone wants to join Russia, they should move to Russia.

The difference is that Taiwan only exists because the losers of the Chinese Civil war ran away to it, and the winners (CCP) were not allowed by the US to finish the job. So for the CCP, Taiwan has always been a problem still left to resolve, an American thorn in their side. It was along the main reasons for them joining the Korean war, because the monumentally dumb McArthur publicly praised and supported Chiang (the leader of the losers of the civil war, the KMT), which led to CCP fears the US will use the Korean peninsula as a sprinboard to attack them and install Chiang back to power.

So while self-determination trumps those concerns for my personal view, I can totally see where China (CCP) is coming from. Especially with a very aggressive American stance against them, why would they want to keep a very friendly to the US runaway province out there?

For Americans, imagine the Confederates ran away to Puerto Rico, force assimilated the locals, and became very friendly with Russia. For the French, that a Bonaparte was ruling Corsica while being friendly with the big bad wolf (depending on the age, Brits or Russians maybe). And on and on.