Ding ding ding! China is slowly but very noisily attempting to tighten it's grip along her Pacific coastline, and it's a very wide grip that stretches from the far north to the far south.
The regional hegemony is very murky and relationship-of-convenience is the norm, especially since there is a lot of very dark history between major regional powers (China, Korea, Japan) and minor ones (Vietnam, Thailand/Cambodia, Philippines, Indonesia, Malaysia). I'm not even going to attempt a short analysis of China's reunification policies towards Taiwan, other than both sides would prefer to remain amicable.
The only "proper" enemy would be Russia, and therefore China signed a border agreement with Russia, basically giving up their claims. Because Russia is stong enough to not play these silly games the CCP is playing with the weaker neighbors.
Like a common school bully, China is only bullying those that can't defend themselves. Doesn't give China much face, I'd say.