If you had to pick one country that is invasion happy it's not China.
Its regime is somewhat conservative in this regard, but happily orders of invasions of other countries when it sees the need.
Can you think of another country that actually does more invasions all the time in recent history?
You can ask all the rhetorical questions you want.
I just don't see a need for pretensions that China does not cynically invade countries on occasion, or similar nonsense.
The death toll on two of the interventions above (2M+ each for Korea/Cambodia), BTW.