China has painted itself into a diplomatic and legal corner regarding its claims in the South China Sea. Its infamous and ambiguous “historic” nine-dash line has been variously interpreted by rival claimants as a national boundary; a sovereignty claim to all water and land within it; and, more optimistically, as an indicator of a sovereignty claim only to the islands and reefs and some submerged features it encloses.
The first two interpretations and China’s frequent and expanding naval exercises in the South China Sea frighten smaller and weaker Southeast Asian countries and serve as convenient targets for US and Japanese anti-China propaganda.
Indeed, China has been under withering political and legal attack for allegedly violating the 1982 UN Convention on the Law of the Sea, which it ratified in 1996.