Like the South China Sea, the East China Sea has been an area of much contention. China's long-standing feud with Japan has continued with friction over the Diaoyu Islands, which both countries lay claim to, and arguments over who owns a swathe of sea territory. China is also at loggerheads with South Korea over Socotra Rock, a submerged reef that hosts a Korean scientific research station, and which Beijing says intrudes on its Exclusive Economic Zone (EEZ).