As I've noted in the past, we used to conduct phony FONOPs (freedom of navigation operations) in the South China Sea. We just conducted innocent passage--which does not challenge illegal territorial claims--rather than true FONOPS that defy such claims.
So loud protests by China were enough without actions. If China is deliberately risking collisions and perhaps armed conflict, that's worrisome:
What makes this [latest near-collision] incident - and other recent maritime clashes - so disconcerting, US naval analysts and sources note, is that the USN and PLAN ships are supposed to be operating under the Code for Unplanned Encounters at Sea (CUES): an agreement reached at the 2014 Western Pacific Naval Symposium to reduce the chance of an incident at sea between the countries.
The USN was able to persuade China to join CUES following a similar incident that occurred in the same area in December 2013. In the earlier clash, guided-missile cruiser USS Cowpens (CG 63) was on a solo patrol in the region and diverted to conduct an intelligence-gathering mission on initial multiship operations involving the new Chinese carrier Liaoning[.]
We need to make sure we have plenty of overwatch on our ships and planes challenging Chinese illegal claims to control international waters. We really don't want one of our warships disabled and towed back to a Chinese port in a "rescue" operation after an "accident."