Increasingly assertive territorial claims over islands, reefs, shoals and waters have raised the risk of conflict erupting in the South China Sea.
The tussle between China and some South-east Asian nations is over resources as much as it is over territory.
The South China Sea contains some of the world's most important and busiest sea lanes and ports. In a year, it sees thrice the amount of container traffic than does the Suez Canal and over five times that of the Panama Canal. Half of the world's global oil tanker shipments pass through its waters. Five of the world's top 10 busiest ports are located here.
It also has valuable undersea deposits of proven and potential petroleum and natural gas reserves. According to the World Bank, the proven oil reserves stand at least 7 billion barrels of oil and 900 trillion cubic feet of gas. Some other estimates have pegged hydrocarbon deposits here at even higher and some Chinese media have dubbed this area the "second Persian Gulf". That said, the commercial viability of oil exploration here remains largely unproven.
In addition, the South China Sea has productive - but fast-depleting - fishing grounds, which are a vital source of food and livelihood in the region. Its waters also host a rich bio-diversity of species.
The row, at the same time, is about the changing geo-strategic configurations. China's growing profile as a military power, trading partner and investor challenges the long-established US presence in the region.
Who claims what?
The most heated territorial disputes are about the Spratly Islands, the Paracel Islands and the Scarborough Shoal.
The Spratlys, rich in hydrocarbon deposits and fishing grounds, consist of over a hundred tiny islands and reefs measuring no more than 5 square km. They are claimed, in whole, by China, Taiwan and Vietnam. Malaysia and the Philippines lay claim to portions of these islands. Brunei claims a continental shelf that overlaps a southern reef but has not formally staked the reef itself.It claims an exclusive economic zone over this area. Some 45 islands are occupied by small military contingents from China, Malaysia, the Philippines, Vietnam and Taiwan. Malaysia built a resort and an airstrip on the Swallow Reef here in 1991, raising protests from other claimants. In 2009, it made a joint submission with Vietnam to the UN Convention on the Laws of the Seas, clarifying its position on the limits of the continental shelf. The Philippines has accused China of beefing up its military footprint in the Spratlys, and engaged in a number of maritime standoffs since 2012. The two countries have accused each other of intrusions, especially in the Scarborough Shoals.
The Paracels, surrounded by potential oil and gas reserves and containing rich fish stocks, consist of 130 small coral islands and reefs with an area of less than 8 square km. They were annexed by French Indo-China annexed in 1932 and maintained by Vietnam thereafter. Vietnam claims it has documents showing it had ruled these islands since the 17th century. In 1974, Chinese troops clashed with a Vietnamese garrison manning the western islands, and went on to occupy the islands. China maintains an airstrip, a harbour and some 1,000 troops there. In 2012, China created Sansha City, an administrative body with headquarters in the Paracels, to oversee its South China Sea territories. in 2014, it moved a $1billion mobile oil rig in waters off the Paracel islands, sparking multiple collisions between Chinese and Vietnamese ships and deadly riots that targeted Chinese factories in Vietnamese cities.The islands are also claimed by Taiwan.
The nine-dash line: China claims almost the entire South China Sea on a historical basis, saying the area was part of its territory for 2,000 years. It laid out its claims in 1947 on a map with "nine-dash" lines that demarcate almost 80 per cent of the South China Sea as its territory. It submitted this map to the UN in 2009, raising protests from other claimant nations. In 2012, it issued new passports that reflected its South China Sea claims as its territories. In early 2013, the Philippines launched an arbitration case under UNCLOS, contesting China's claims in the South China Sea. Taiwan also uses the 1947, which was issued by , as the basis to stake its own claims in the South China Sea.
How are the disputes being resolved?
The overlapping territorial claims to sovereignty and maritime boundaries are usually resolved through a combination of customary international law, adjudication before the International Court of Justice or the International Tribunal for the Law of the Sea, or arbitration under Annex VII of the United Nations Convention on the Law of the Sea (UNCLOS). China has ratified UNCLOS but the treaty rejects “historically-based” claims which Beijing uses.China wants to use closed-door, bilateral negotiations to solve the disputes. But the other claimants distrust these methods which place them at a disadvantage before a more powerful China. The Philippines, which uses geographical proximity as the basis for its claims, sought international mediation in 2013, lodging an arbitration case before UNCLOS to dispute China's claims. Even if the UN rules in Manila's favour, Beijing is under no obligation to heeds to its non-binding judgement.The ASEAN has also initiated attempts at conflict resolution but with limited success. Under its auspices, the claimant nations signed the "Declaration on the Conduct of Parties in the South China Sea" in 2002. Although this eased tensions somewhat, it has not brought about the legally-binding "Code of Conduct" which would oblige.The US takes no position in the South China Sea territorial disputes but has condemned as "provocative" what it calls China's attempts to advance its claims over disputed territories in a manner that undermine peace and stability in the region.Washington helps train Philippines troops and is helping modernise its military assets and equipment. In April 2014, the two countries signed a 10-year pact to allow US troops, ships and aircraft better access to Philippine bases and facilities.
Analysts note China's concerted moves to pursue and strengthen its stakes to territory in the South China Sea and expect China to continue to act unilaterally in the region until it meets concerted resistance, whether diplomatic or military.
The possibility of joint development of resources, like fishing and hydrocarbons, has been mooted as a solution. But growing nationalism in all quarters limits the scope of such ventures.