Sources: Asia Maritime Transparency Institute, US Department of Defense

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During 70 years of competing claims in the region, all claimants have repeatedly pledged to pursue diplomatic means to resolve disputes, with multiple pledges made to resist pursuing military build-ups on disputed islands.

In keeping with those pledges, there has historically been little serious military development in the region. Areas were patrolled by navies and semi-permanent outposts were established, but permanent military installations were often unsustainable due to the tiny available land areas on the maritime features.

In 2014 and 2015, mainland China undertook large-scale construction of seven island facilities capable of supporting military activity on top of maritime features: Subi Reef, Mischief Reef, Johnson South Reef, Hughes Reef, Gaven Reef, Fiery Cross Reef and Cuarteron Reef.

Beijing denies that this constitutes militarisation, but Asean ministers have voiced “serious concern” about the developments.

Reef reclamations

Fiery Cross Reef

Total area reclaimed

2,740,000 square metres reclaimed, the equivalent to 33 times the total area of the Hong Kong Convention Centre.

Fiery Cross Reef was first occupied by mainland China in 1988, under a charter to build weather stations for the UN, whose scientists later admitted were unaware of the territorial disputes in the region. From a natural landmass of less than 10,000 square metres, the island has been expanded to almost 3 sq km. Fiery Cross Reef is the most isolated maritime feature occupied by Beijing in the Spratlys, and the work done away from easy surveillance has been the most extensive. New facilities include a 3.1km airstrip, long enough to allow any Chinese military aircraft to land. Beijing has also begun development of port facilities which may be capable of docking military tankers.

PLA Navy troops patrol near a sign in the Spratly Islands reading "Nansha is our national land, sacred and inviolable".
Photo: Reuters

Subi Reef

Total area reclaimed

3,950,000 square metres reclaimed, the equivalent to 47 times the total area of the Hong Kong Convention Centre.

Subi Reef was occupied by mainland China in 1988 and has been its northernmost outpost in the Spratly Island grouping since then. In its natural state, the reef was submerged at high tide, but construction has transformed the reef into a permanent military facility. The reef is 14km from the Thitu Reef cluster occupied by the Philippine military.

The oil red herring

Though conflict in the South China Sea is often depicted as a contest for resources, a look at surveying map of oil and gas in the region tells a different story.

Much of the oil-rich territory in the region is uncontested, falling within clearly defined waters north of Malaysia and Brunei, or off the southern coast of Vietnam.

Resource development is often hotly contested. The Malampaya oil rig northwest of Palawan met initial Chinese resistance, and the Haiyang Shiyou 981 placement west of the Paracels triggered widespread rioting in Vietnam.

But participants were willing to brave the conflicts not merely for the resources themselves, but for the precedent of stewardship established by developing resources in the disputed regions. Officials and maritime lawyers argue these instances can later be pointed to as evidence of effective jurisdiction in order to later secure recognised legitimacy in international settlements.

Mischief Reef

Total area reclaimed

5,580,000 square metres reclaimed, the equivalent to 67 times the total area of the Hong Kong Convention Centre.

Construction on Mischief Reef began in 1994, under protest from the Philippine government. Mischief Reef lies just 129 nautical miles (239km) from the Philippine island of Palawan, within the Philippines’ exclusive economic zone under UNCLOS, while mainland China’s Hainan Island is 599 nautical miles (1,109km) away. Before construction began, little if any land remained permanently above water at Mischief Reef, but ongoing reclamation has established more than 5 sq km of permanent land mass. The Asian Maritime Transparency Institute speculates that the widened mouth of the reef reveals China’s intention to use Mischief Reef as a large scale naval facility, complementing the air force capabilities constructed at Fiery Cross Reef.

Gaven Reef

Total area reclaimed

136,000 square metres reclaimed, the equivalent to 19 times the total area of the Hong Kong Stadium Field.

Chinese construction at Gaven Reef in the Tizard Banks began after March 30, 2014. From little available land mass, a new artificial island was built, in an approximately 300 metre by 250 metre square. In addition a channel was also cut out of the centre of the reef. The new structures include a main square building with what appears to be an anti-aircraft tower, a large supply platform where ships can dock, several gun emplacements, as well as radar and communications equipment

The government headquarters in Sansha, China's newest city, on Woody Island in the Paracels.
Photo: AFP.

Hughes Reef

Total area reclaimed

76,000 square metres reclaimed, the equivalent to 10 times the total area of the Hong Kong Stadium Field.

In 2004, Hughes Reef was a 380 square metre concrete platform, but after reclamations began in the summer of 2014, the land mass at the reef has increased to 75,000 square metres. The facility on Hughes comprises a main, square building and an anti-aircraft tower.

Johnson South Reef

Total area reclaimed

109,000 square metres reclaimed, the equivalent to 15 times the total area of the Hong Kong Stadium Field.

Johnson South Reef was a 7.2 sq km submerged reef in the Union Banks until early 2014. Where there was once just a small concrete platform and communications facility, there now stands an island that is 400 metres across at its widest point. It has an area of more than 100,000 square metres and features a sea fortress with the following facilities.

Cuarteron Reef

Total area reclaimed

231,100 square metres reclaimed, the equivalent to 3 times the total area of the Hong Kong Convention Centre.

Cuarteron Reef, located in the London Reefs, was also the site of significant dredging and construction during the summer months of 2014. Before that, the reef held a concrete supply platform with communications equipment and radars, like many of mainland China’s other land features in the Spratly Islands. As imagery from November 2014 demonstrates, China has since built an artificial island at Cuarteron and is also building structures on the island.

Conflict Zones

Battle of the Paracels

The January 1974 battle of the Paracel Islands, between the People’s Liberation Army Navy and the South Vietnamese Navy, was the PLA Navy’s first sea battle against an external enemy. When it was over, China had gained control over the whole Paracel archipelago in the South China Sea. Accounts of the battle vary widely, but an article this year by Professor Toshi Yoshihara from the US Naval War College, drawing on new Chinese sources, sets out a clear timeline.

Yoshihara notes that Mao Zedong issued his last military orders during the conflict and that Deng Xiaoping oversaw the naval campaign, evidence of the importance placed on it by the Chinese leadership.

Johnson South Reef Skirmish

In the most recent major military clash in the South China Sea, the Chinese and Vietnamese navies exchanged fire at Johnson South Reef in the Spratly Islands on March 14, 1988, with 64 Vietnamese troops reported killed and three Vietnamese ships sunk.

The Chinese side said it took place a year after Unesco entrusted China to set up an oceanographic station on Fiery Cross Reef, and that the PLA Navy sent three frigates to protect the construction mission and safeguard China’s territorial sovereignty because Vietnam had attempted to occupy Fiery Cross Reef, Johnson South Reef and other Chinese-controlled outcrops in the Spratlys.

A video of the clash released by the PLA Navy in 2009 to celebrate its 60th anniversary claimed the Chinese side killed more than 300 enemy troops, captured nine others, sank one foreign warship and damaged other two, while just one PLA sailor was injured.

In his book The South China Sea, former BBC reporter Bill Hayton said the Vietnamese appeared to have landed on the reef in a small boat loaded with construction equipment, before proceeding to raise Vietnamese flags. Chinese troops then arrived and tried to remove the flags, with the two sides shouting at each other and then scuffling.

He cites the Chinese side as saying a Vietnamese soldier shot and wounded a Chinese one, and that the Chinese force then retreated as Vietnamese ships opened fire with machine guns, whereas the Vietnamese said the Chinese killed the deputy commander of the Vietnamese landing force and then withdrew before their ships opened fire.

The video shows the Vietnamese force standing on the reef, knee-deep in water, before the Chinese ships open fire, mowing them down.