Is China a Party to the Law of the Sea Treaty?

China claims about 90% of the South China Sea, not as an informal zone of influence but as its territorial waters right so it's basically like if the United States said our territorial waters extend to the coast of Venezuela and that would be the relevant comparison here. The area that is disputed between China and India is the size of like a small European country. And so we've got the international law against trans border aggression and our repeated invasion of countries without the authority to security council. It does seem to me it would be nice to work hard to actually figure out a way to ease their concerns right to make them feel less threatened.