There isn't in the case of Ukraine either, but NATO has mostly stepped up anyway. Sure we are not putting troops on the ground (yet???) but NATO has provided a lot of support.
Countries like South Korea, Japan, Philippians, and Australia are likely to get scared if China does too much and send some form of help.
Nowhere. The relevant alliances are AUKUS [1] and the Quad [2].
[1] https://en.m.wikipedia.org/wiki/AUKUS
[2] https://en.m.wikipedia.org/wiki/Quadrilateral_Security_Dialo...