The scary new map of the South China Sea

A major redrawing of the map of the South China Sea began when Xi Jinping came to power in 2012. In the subsequent three years China built seven new bases in the Spratly Islands, three of them with large airfields, on rocks and reefs otherwise contested by the Philippines, Vietnam, Malaysia and Taiwan (see map). These bases now play host to a large, permanent presence of Chinese troops, ships and aircraft, as well as advanced intelligence capabilities. Before, the most elaborate constructions built by any country consisted of short airfields on some islands or outposts on stilts atop the coral reefs.

China has placed great rhetorical weight on its vague claim to that part of the South China Sea (ie, nearly all of it) which falls within its “nine-dash line”. Sometimes the dashes move around on official maps; occasionally a tenth dash is added next to Taiwan. Yet despite the vociferousness of China’s claims and the ambiguity of its supposed boundary, an uneasy status quo emerged over the past half decade or so.

On any given day one or more Chinese coast guard ships and anywhere between a few and a few dozen “maritime militia” vessels (typically large fishing vessels) have been stationed at disputed rocks and reefs throughout the sea. Until recently their remit has usually been limited. The vast bulk of commercial shipping activity, including container flows on some of the world’s busiest sea-lanes, has been unaffected. China’s military and law enforcement have notionally been preoccupied with a smaller goal: preventing energy exploration and fishing within the area.

Even then their enforcement has been lacklustre: a ban by China on fishing in the South China Sea every summer (formally to help replenish stocks) has not been seriously applied. The American navy has maintained the practice of sailing through the islands on “freedom of navigation” operations, challenging China’s claims to the area, having renewed such operations in 2015. Yet the number of such sailings has tailed off and China has issued mainly routine objections to them. Meanwhile the Philippines and sometimes Vietnam urged the Association of Southeast Asian Nations (ASEAN) to issue fresh statements of concern, to little effect. Don’t say it too loud, but for an epicentre of a superpower contest, the South China Sea was often surprisingly placid.

Compared with that, the squalls in this new phase of the confrontation threaten to become a storm. The Philippines, Vietnam and Malaysia have begun to rebuff China more forcefully. In order to grasp this dynamic, it is important to consider the relative tension levels across the area. Calmest of all are the Paracel Islands. China has occupied their entirety since seizing them from Vietnam in a battle in 1974. On the largest of the 130 islands, China has an airfield which has hosted combat aircraft.

More tense is Scarborough Shoal, a single isolated lagoon. Its proximity to Manila, the capital of the Philippines, arguably makes it the South China Sea’s most strategically important feature. Before 2012 Philippine vessels plied the lagoon’s rich fisheries, and the Philippine navy would expel Chinese vessels that tried to do the same. But that year, Chinese coast guard vessels forced the Philippine ships out. Brazenly, China has controlled it since.

Most fraught of all are the Spratly Islands. The Chinese construction of large bases from 2013 to 2016 was on reclaimed land there. As a result the islands are now where the push back is most fulsome. Since 2022 Vietnam has been dredging and reclaiming land on features that it occupies: it has now built up about half as much land as China has reclaimed (see chart), and appears to be constructing a large airfield. The Chinese government has remained silent on this matter. Malaysia has sought cosy relations with China and tolerated Chinese ships in the waters it claims as its exclusive economic zone. It has also turned a blind eye or worse to fleets carrying sanctioned Iranian oil that transfer it to China-bound vessels. Even so, Malaysia depends on energy revenues and as a result has restarted oil and gas exploration off the coast of Borneo, close to the Spratlys, in the face of Chinese objections.

The biggest push back is coming from the Philippines. President Ferdinand “Bongbong” Marcos has directed his officials to shine a spotlight on Chinese activity in the Spratlys, including within the Philippines’ 200 nautical-mile (370.4km) exclusive economic zone. Of particular note has been China’s mission to prevent resupply of a Philippine Navy vessel, the Sierra Madre, which was grounded in 1999 on Second Thomas Shoal. Last year the Philippines began using coast guard ships to escort construction materials to the Sierra Madre to reinforce its rusting hull. China responded and by June 2024 had successfully blocked resupply of the Sierra Madre for four months. The small platoon of Philippine marines guarding her had begun to run out of food and water. Finally, when the Philippine navy mounted an attempt on June 17th, Chinese coast guardsmen armed with axes boarded the Philippine dinghies as they reached the shoal and disarmed the sailors by force. (The Philippine sailors followed orders not to fight back, but one lost a thumb.)

In July China and the Philippines stepped back from a bigger confrontation, chastened at least for now. Chinese diplomats accepted a long-standing invitation from the Philippines to fly to Manila for talks. In the negotiations that followed, they agreed to “provisional arrangements” which would allow regular resupply of the Sierra Madre. Under the agreement, China will “inspect” the resupply missions from a distance of several hundred metres to ensure that they are not bringing in construction materials. But Philippine officials say that the Sierra Madre has nonetheless been stabilised with concrete and won’t float away (or fall apart) anytime soon. All in all, a tentative victory for the Philippines.

Elsewhere, however, tensions are growing, not least at Sabina Shoal, where Chinese ships rammed the Teresa Magbanua. Philippine officials say that they sent their ship to the shoal because they had seen signs that China was preparing to build something there. But they are playing a risky game. The Philippines had no continuous presence at the lagoon before April, so it is changing the status quo, which China abhors. Nor is it clear that American alliance guarantees to the Philippines apply at Sabina Shoal, as they almost certainly do at Second Thomas Shoal. Under a mutual defence treaty, America commits to “meet the common dangers” should there be an attack on a Philippine public vessel; but while the Sierra Madre is fixed to Second Thomas Shoal with cement, Teresa Magbanua is afloat and so might be removed.

The narrow significance of the Sabina incident is that it could yet spark a military encounter at sea. China might make more aggressive attempts to bully the Philippines out of the shoal. The broader implications go far beyond a few rocks and ships, since such an encounter would test America’s appetite to come to the aid of the Philippines: risking American lives and treasure over an uninhabited shoal would be unpopular in Washington. Yet if the Philippines retreats it is unlikely to get the shoal back. That would trigger memories of its loss of Scarborough Shoal in 2012, and prompt questions in Manila about the reliability of its bigger treaty ally.

The past few months therefore offer two starkly different visions of how the South China Sea will operate in the 2020s and beyond. One, based on the Sierra Madre episode, points to the sea being a contested zone where all parties nonetheless are capable of de-escalating and developing common understandings around flashpoints. The other vision can be found at Teresa Magbanua: a constantly shifting set of mini-confrontations in which China seeks to enforce its will on the sea and South-East Asian countries push back. When the repelling is carried out by formal allies, it puts America in a horrible dilemma: does it back them up or urge them to back down? China will watch like a hawk what happens next. So will other American allies in Asia and beyond.

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