There is a lot of dispute over who owns which waters in the Pacific.
These kinds of interactions have been the norm for over a decade.
Everyone claims everything, and there are a great many disputed areas.
US allyship allowed Phillipines and Japan to exert outsized naval claims post-WWII.
It isn't surprising that as China increases in strength while the US wanes, that they are claiming more ocean territory.
What happens when the (world) police don't show up?