I don't think you understand how International Court run, base on your argument, US should never lose any case in International Court, but in true US had lose quite a number of the court case brought up into International Court.
There are no long lasting friends and enemy at least where nationals is consider. I always come down to nationals interest. Thus if China expect Russia to support them in the future if it hurt Russia, then they will be in a rough surprise. Similar China will not support Russia if it hurt China interest.
Problem is many in China don't see it this way and those is why China have many conflict to nearly all the neighboring countries. It might happen to 1 or 2 neighboring countries and having conflicting of interest with nearly all the neighboring is bad