Scarborough Shoal Standoff: More Deterrence, Less Trust

When China announced on 10 September the establishment of a national nature reserve on Huangyan Island (known internationally as Scarborough Shoal), it was not simply another bureaucratic move. It was a signal that underscored Beijing’s intent to consolidate its control over a strategic maritime feature long contested by the Philippines. Rather than cooling tensions, however, the decision has injected new dynamics into an already volatile situation.

Scarborough Shoal has long occupied a sensitive position in the South China Sea. It sits at the key point of what some Chinese analysts call the country’s “iron triangle” of maritime control, linking the Xisha (Paracel), Zhongsha (Macclesfield Bank and Scarborough), and Nansha (Spratly) island chains. Compared with China’s strong military footholds in the Paracel and Spratly groups, its presence in the Zhongsha area remains the weakest link. Strengthening control over Scarborough helps close that gap, enhancing China’s ability to monitor and potentially deter naval and air movements through the South China Sea. It also carries implications for the Taiwan Strait, where any escalation would inevitably draw on Chinese assets and logistics across the region.

Among the contested features of the South China Sea, Scarborough Shoal is unique.

China’s Iron Triangle

First, the lack of permanent Chinese facilities on Scarborough means China’s hold over the shoal remains tenuous. China’s control there is weaker than that over other occupied features. Sustaining control demands costly and continuous patrols, leaving it vulnerable to Philippine interference.

Second, the shoal lies near key Philippine strongholds such as Subic Bay and Cesar Basa Air Base, both of which are accessible to US forces under the Enhanced Defense Cooperation Agreement (EDCA). For Manila and Washington, this proximity magnifies its strategic importance in any contingency involving China. For Beijing, therefore, retaining control of Scarborough is not only about sovereignty — it is about preventing encirclement in a Taiwan Strait contingency.

Third, if Manila were to take steps that China deemed to undermine the One China principle, Beijing could justify taking more assertive measures at the shoal. This could potentially include the construction of permanent facilities in response to Manila’s interference in what China deems to be its domestic affairs.

The Philippine government views China’s move with deep concerns. Two of them stand out. The first is the erosion of sovereignty: Beijing’s establishment of a national nature reserve could entrench its de facto control and, over time, harden into a fait accompli. The second is the prospect of militarisation: that China might eventually build a permanent base and threaten the Philippines’ northern approaches. These anxieties help to explain Manila’s stepped-up maritime patrols and frequent coast guard deployments near the shoal. These efforts aim to break China’s blockade of the shoal and signal Manila’s intention to maintain a continued presence in the area.

For Manila, Scarborough represents both a legal and national security test. Backed by the 2016 arbitral award rejecting China’s nine-dash line claims, the Philippines asserts sovereign rights over the shoal and its surrounding waters. Domestically, there is strong political consensus behind defending these rights, while alliance coordination with the US — recently reinforced by expanded base access under EDCA — provides strategic confidence.

Over the coming decade, Scarborough is likely to remain under China’s effective control, with the Philippines persisting in legal, diplomatic and alliance-based resistance.

Yet this tightening alignment has not gone unnoticed in Beijing. The Philippines’ growing readiness to cooperate with Washington in a potential Taiwan Strait contingency has deepened Chinese suspicions about Manila’s long-term intentions. From Beijing’s perspective, Scarborough Shoal is no longer just a bilateral maritime dispute; it has become a frontline position in a wider US-led containment strategy. This perception has prompted a noticeably harder line: firmer law enforcement patrols, the announcement of the nature reserve, and an expanding administrative and ecological presence around the shoal.

By declaring the area a protected marine zone, China can strengthen administrative and legal claims while maintaining the appearance of restraint. Conversely, large-scale reclamation or base construction would contradict its conservation rhetoric and invite international backlash. It is more likely that China would deploy small observation posts or semi-permanent platforms to sustain coast guard operations. These are incremental steps that reinforce presence without overt militarisation.

This pattern reflects a strategic balance of assertiveness and caution. Scarborough is more than 800km from China’s nearest supply base on the mainland, making sustained patrols costly (Scarborough cannot be resupplied by China’s occupied islets in the Spratly/ Nansha Islands, which are located at least 600km to the southwest of the shoal. Both Scarborough and the Nansha islets need to be resupplied from bases on the Chinese mainland). Yet ceding ground would be politically unthinkable for Beijing, especially as it perceives the Philippines drifting closer to Washington’s in its defence planning with regard to Taiwan. For both sides, endurance has become the strategy.

Over the coming decade, Scarborough is likely to remain under China’s effective control, with the Philippines persisting in legal, diplomatic, and alliance-based resistance. One would expect recurring low-level clashes — water-cannon incidents, blocking manoeuvres and close-quarter standoffs — punctuated by temporary crises that raise regional alarm.

Three scenarios illustrate the path ahead.

First, consolidation and normalisation would be the most probable outcome. China deepens administrative control and ecological management. In response, Manila would provide additional funding for expanded fishing activities and conduct more frequent “resupply” missions. It might leverage assertive transparency — releasing footage of incidents with the Chinese Coast Guard and diplomatic notes — alongside multilateral diplomacy and alliance deterrence. The result is a tense equilibrium of persistence without war.

Second, there would be periodic crises involving repeated maritime run-ins which trigger diplomatic flare-ups and sharper foreign responses. This would increase the risk of miscalculation.

The third and last scenario involves escalation: A Taiwan Strait crisis or a major U.S.-Philippine operation could provoke direct Chinese countermeasures near Scarborough. This would transform the shoal into a potential military flashpoint.

The Scarborough standoff thus mirrors the South China Sea’s broader dilemma: a fragile balance sustained by deterrence and symbolism rather than trust. As Manila leans closer to Washington’s Taiwan calculus, Beijing is hardening its response. This would ensure that Scarborough becomes both a test of endurance and a barometer of regional order.

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