Land grabbing.

From PLAs 2003 speech:

"The first issue is living space. This is the biggest focus of the revitalization of the Chinese race. In my last speech, I said that the fight over basic living resources - including land and ocean- is the source of majority of wars in history. (...) Not only our ability to sustain and develop our race, but even it's survival is gravely threatened, to a degree much greater than faced by Germany back then.(...) To solve this problem we must lead the Chinese people outside of China, so that they could develop outside of China"

https://www.trunews.com/stream/chinese-general-pla-must-kill-all-americans-with-biological-weapons