however, have erupted in the last two years, involving Vietnam, the Philippines and China, which claims the busy waterway virtually in its entirety.
Concerns have been exacerbated by China's deployment of a patrol ship, equipped with a helipad, to guard its claimed areas and establishment last year of what they called Sansha city on a remote island to administer territories being contested by rival claimant countries.
A tense standoff that erupted last year between Chinese and Filipino ships over the Scarborough Shoal has remained unresolved, prompting the Philippines in January to take a daring legal step that challenged China's vast claims before a tribunal under the United Nations Convention on the Law of the Sea. China has ignored the move.