COMMENTARY: Scarborough Shoal 2026 — Does the American Alliance Do Enough to Curb China in the Philippines?

Introduction: A Floating Platform and a Burning Strategic Question

How It Started: a 30-Square-Meter Structure That Alarmed the World

In May 2026, Philippine authorities detected via satellite surveillance and maritime patrols a floating platform anchored inside the lagoon of Scarborough Shoal (Bajo de Masinloc), approximately 200 kilometers from the coast of Luzon, the Philippines' main island. The structure measured roughly 5 to 7 meters in length, with a deck area of approximately 30 square meters, equipped with a communications antenna and carrying Chinese nationals. The chief of the Armed Forces of the Philippines (AFP), General Romeo Brawner Jr., confirmed its presence and noted it appeared to be used for data collection.

Manila filed a formal diplomatic protest. Beijing responded that the platform was "a temporary scientific research installation for coral study," operated by the Chinese Academy of Sciences. The platform was withdrawn around June 17 — but a week after its disappearance, the Chinese research vessel Tong Ji appeared in the same area, accompanied by Chinese coast guard ships and maritime militia vessels. Philippine Defence Secretary Gilberto Teodoro Jr. summed up the situation to the Wall Street Journal: "If it's the precursor to a more permanent presence, or a malicious activity, that is concerning."

An Atoll Crystallizing Fifteen Years of Tensions

Scarborough Shoal is not merely 150 square kilometers of reefs and lagoons. Since China seized de facto control during the 2012 confrontation with the Philippines — then betrayed the mutual withdrawal agreement brokered by Washington — this shoal has become the most eloquent symbol of Chinese maritime expansionism in the South China Sea. In 2016, the Permanent Court of Arbitration in The Hague invalidated China's claims over the entire South China Sea, including Scarborough, declaring them illegal under international law (UNCLOS). Beijing ignored the ruling, dismissing it as "a piece of paper."

Since then, China's strategy has been a classic demonstration of the so-called "salami slicing" approach — advancing step by step, gradually, staying below the threshold that would trigger a direct military response. In September 2025, China had unilaterally declared a "national nature reserve" covering roughly 3,500 hectares of the shoal. In spring 2026, the AFP tracked 82 Chinese vessels (coast guard and navy) in the Philippine exclusive economic zone in May alone, with 39 around Scarborough. The floating platform is no accident — it is a test.

The American-Philippine Alliance: Solid on Paper; Nuanced in Practice

The 1951 Mutual Defence Treaty and Its Ambiguities

The Philippines and the United States are bound by the Mutual Defence Treaty of 1951, which commits Washington to defend Manila in the event of an armed attack. In 2023 and 2024, the Biden administration clarified that this treaty applies to Philippine armed forces, aircraft, and government vessels in the South China Sea. That clarification was maintained by the Trump administration. On paper, if a Philippine coast guard vessel is attacked at Scarborough, Washington is committed.

But practice differs sharply. China uses precisely the tactics designed to stay below the threshold of what would qualify as an "armed attack": water cannons, blockades, harassment, "research" structures. Faced with a floating scientific platform, the 1951 treaty does not automatically activate. Washington responded with symbolic measures: on June 22, during a ceremony at Subic Bay naval base, the United States transferred to the Philippines four Ocean Aero Triton autonomous underwater vehicles — solar-powered marine drones capable of monitoring waters for up to 30 days without human intervention. Total value: 13 million dollars. A useful investment, but far from a deterrent against a Chinese navy deploying destroyers.

Joint Military Exercises and Their Limits

The United States and the Philippines conducted their first joint patrol exercises in proximity to Scarborough Shoal in May 2026 — a historic first. Washington also announced plans to deploy additional missile launchers in the Philippines, which prompted vigorous protests from Beijing. These measures send a solidarity signal — but they do not alter China's fundamental calculations regarding Scarborough, which Beijing has considered its territory since 2012.

Philippine Defence Secretary Teodoro told the Financial Times that Manila's level of concern is "significantly higher than ever." The AFP declared it would not permit the construction of permanent structures on the atoll. But the Philippines' real military options remain limited: their navy is outdated, their coast guard under-equipped, and their capacity to physically contest a Chinese presence without direct American support is weak. That power asymmetry is the alliance's true vulnerability.

Why China Persists Despite the American Presence

China's Strategy at Scarborough: Testing the Red Lines

According to analysis by the ISW published on June 26, 2026, China will likely continue efforts to assert its territorial claims over Scarborough Shoal and expand its presence under the cover of conservation and research activities. The withdrawn floating platform is not necessarily abandoned — it is one phase of a process. As Asia Times notes, Beijing "may be willing to adjust tactics when costs rise, but without necessarily modifying its long-term strategy." China has not yet built any permanent structure at Scarborough — but its behavior since 2012 follows exactly the same pattern observed at Mischief Reef before it became a military base.

China has three structural advantages the American-Philippine alliance cannot easily counter. First, geographic proximity: Scarborough is 860 kilometers from Hainan island, far closer than the US base at Guam. Second, continuity: China's presence in the area is permanent, while US presence rotates. Third, ambiguity: China acts in grey zones that do not trigger alliance mechanisms but gradually erode Philippine sovereignty.

The Philippine Temptation to Diversify Partnerships

Confronted with these limits, the Philippines is seeking to diversify its security partnerships. Manila has signed military cooperation agreements with Japan, Australia, and several ASEAN nations. This networking strategy is logical — but it does not resolve the central problem: none of these partners can replace American military power as a deterrent factor, and Washington itself shows limits in its willingness to confront Beijing directly in grey zones.

Asia Times notes that the Scarborough episode "revealed a far more durable strategy for cementing China's control over the South China Sea" — a strategy combining science, administrative presence, maritime militia, and diplomatic attrition. This reality forces Manila to consider asymmetric responses: improving maritime domain awareness with tools like Triton drones, developing anti-access capabilities that raise the cost of a potential Chinese military operation, and maintaining constant international diplomatic pressure over UNCLOS.

The West Facing the Chinese Challenge in Asian Seas

What Is at Stake for Global Freedom of Navigation

The South China Sea carries approximately 3 trillion dollars in global trade annually. If Chinese claims were accepted de facto through the absence of effective contestation, that trade would become subject to Beijing's discretion. That is precisely why freedom of navigation remains a vital American interest — not out of sentimentality for the Philippines, but because control of Asian maritime routes by a non-democratic state would represent a major geopolitical shift for the entire global trading system.

The Scarborough affair fits within a broader context of China's military buildup. The People's Liberation Army Navy (PLAN) added more naval tonnage between 2021 and 2025 than the United States. China is building its own aircraft carriers, blue-water destroyers, and nuclear-armed submarines. In that tableau, a 30-square-meter platform at Scarborough is anecdotal — but it illustrates the mindset of a power systematically testing the limits of what it can do without triggering a significant response.

Chinese Sanctions Against Teodoro: A Symbolic Escalation

China imposed personal sanctions on Philippine Defence Secretary Teodoro — a direct escalation targeting the individual responsible for the Philippines' military strategy in this matter. This measure reveals an additional dimension of China's strategy: beyond acting in disputed waters, Beijing is attempting to personally intimidate Philippine decision-makers, targeting them in their professional and potentially personal lives. It is a form of psychological pressure that goes beyond simple state-to-state diplomacy and reaches the individuals defending Philippine interests.

This symbolic escalation had a counterproductive effect: it hardened the resolve of the AFP and the Philippine government to hold their position. But it illustrates the nature of the adversary: a China confident in its power, impatient with challenges, and willing to deploy every available lever to impose its positions.

The West Facing the Chinese Challenge in Asian Seas

What Is at Stake for Global Freedom of Navigation

The South China Sea carries approximately 3 trillion dollars in global trade annually. If Chinese claims were accepted de facto through the absence of effective contestation, that trade would become subject to Beijing's discretion. That is precisely why freedom of navigation remains a vital American interest — not out of sentimentality for the Philippines, but because control of Asian maritime routes by a non-democratic state would represent a major geopolitical shift for the entire global trading system.

The Scarborough affair fits within a broader context of China's military buildup. The People's Liberation Army Navy (PLAN) added more naval tonnage between 2021 and 2025 than the United States. China is building its own aircraft carriers, blue-water destroyers, and nuclear-armed submarines. In that tableau, a platform of 30 square meters at Scarborough is anecdotal — but it illustrates the mindset of a power systematically testing the limits of what it can do without triggering a significant response.

Chinese Sanctions Against Teodoro: A Symbolic Escalation

China imposed personal sanctions on Philippine Defence Secretary Teodoro — a direct escalation targeting the individual responsible for the Philippines' military strategy in this matter. This measure reveals an additional dimension of China's strategy: beyond acting in disputed waters, Beijing is attempting to personally intimidate Philippine decision-makers, targeting them in their professional and potentially personal lives. It is a form of psychological pressure that transcends simple state-to-state diplomacy.

This symbolic escalation had a counterproductive effect: it hardened the resolve of the AFP and the Philippine government to hold their position. But it illustrates the nature of the adversary: a China confident in its power, impatient with challenges, and willing to deploy every available lever to impose its positions. Sanctioning the defence secretary of a sovereign nation for defending his country's exclusive economic zone — that is geopolitical bullying in its purest form.

The Philippine Temptation to Diversify Partnerships

Beyond Washington: Japan, Australia, and ASEAN

Confronted with the limits of the American alliance in grey zones, the Philippines is seeking to diversify its security partnerships. Manila has signed military cooperation agreements with Japan, Australia, and several ASEAN nations. This networking strategy is logical — but it does not resolve the central problem: none of these partners can replace American military power as a deterrent factor, and Washington itself shows limits in its willingness to directly confront Beijing in grey zones.

Asia Times notes that the Scarborough episode "revealed a far more durable strategy for cementing China's control over the South China Sea" — a strategy combining science, administrative presence, maritime militia, and diplomatic attrition. This reality forces Manila to consider asymmetric responses: improving maritime domain awareness with tools like Triton drones, developing anti-access capabilities that raise the cost of a potential Chinese military operation, and maintaining constant international diplomatic pressure over UNCLOS.

UNCLOS and International Legitimacy

The international legal framework is clear. In 2016, the Permanent Court of Arbitration at The Hague invalidated Chinese claims over the entire South China Sea, including Scarborough, declaring them illegal under UNCLOS. Beijing ignored that ruling, dismissing it as "a piece of paper." This explicit contempt for a binding international legal decision illustrates China's relationship with international law: useful when it serves its interests, ignorable otherwise.

The Philippines have made skillful use of that ruling since 2016 — never pushing to a direct confrontation that their limited military capacity could not sustain. The challenge for Washington is to convert this legal capital into real diplomatic leverage, by coordinating multilateral pressure — with the EU, Japan, Australia — to isolate China on its South China Sea policy. That is harder than transferring Triton drones, but it is the only approach that could alter Beijing's long-term strategic calculations.

The Salami Strategy and Its Worrying Precedents

From Mischief Reef to Scarborough: A Repeated Pattern

The history of Chinese expansionism in the South China Sea since the 1990s is a textbook of graduated encroachment. Mischief Reef, occupied by China in 1995 under the guise of "fishermen's shelters," is today a military base with runways, aircraft hangars, and missile systems. Fiery Cross Reef, Subi Reef — the same scenario repeated itself across several reef formations transformed into artificial islands. Scarborough has not yet followed that path. But its trajectory since 2012 follows exactly the same early-stage pattern.

In 2012, China had promised a mutual withdrawal brokered under US auspices — then stayed. In 2025, it unilaterally declared a "national nature reserve" on part of the shoal. In 2026, it attempted to anchor a "research platform" there. Each step is presentable as innocuous. The accumulation is an occupation strategy. If the AFP is right to declare it will "not permit the construction of permanent structures," it needs the means to prevent the next step — an indefinitely prolonged "temporary" structure — from materializing.

The Implications for Taiwan

The most alarming lesson of Scarborough is not what is happening on that shoal — it is what it says about Beijing's strategic calculations regarding Taiwan. If China can progressively occupy Philippine maritime formations over a decade without triggering a significant American military response, what signal does that send about the resilience of the American commitment in the face of more direct Chinese action in the Western Pacific? ISW analysts note that China will likely continue its efforts to assert territorial claims over Scarborough Shoal in the months ahead.

This reading is shared by American and allied military staffs, which explains why Balikatan exercises between the United States and the Philippines have grown considerably in complexity and scale since 2023. The first joint patrol exercises near Scarborough Shoal in May 2026 — a historic first — are a signal. But a signal is not deterrence. Beijing has seen many, and the floating platform was anchored there all the same.

What the Alliance Should Do in Grey Zones

Developing a Graduated Response Spectrum

One of the most glaring gaps in American South China Sea policy is the absence of a response spectrum between "do nothing" and "direct military intervention." Faced with a Chinese "scientific" platform, the United States transferred autonomous drones worth 13 million dollars — a useful gesture but disproportionately weak relative to the threat. Intermediate options exist: escorting Philippine coast guard vessels with American ships, targeted sanctions against companies supplying the platform's equipment, coordinated diplomatic pressure with the EU and regional allies.

These intermediate options are complicated by American domestic politics and the concern about triggering unintended escalation. But the absence of any mid-spectrum response is precisely what allows the salami strategy to work: Beijing knows nothing between diplomatic silence and war truly threatens it. Changing that calculation — without triggering conflict — is the central strategic challenge the American administration must solve for the American-Philippine alliance to recover its deterrent credibility.

Modernizing Alliance Commitments for the 21st Century

The Mutual Defence Treaty of 1951 was designed for a direct existential threat — not for 30-square-meter platforms equipped with antennas and Chinese nationals. The alliance needs a modernization of its activation mechanisms that explicitly includes the grey-zone tactics that Beijing employs systematically. A bilateral American-Philippine clarification — similar to what Biden had begun and Trump maintained — on the applicability of the treaty to Chinese maritime militia incursions would be a first step. The message from Washington to Manila must be clear: the alliance covers grey zones, not only conventional armed attacks.

The AFP, through joint exercises, has received growing training in navigating these grey zones — knowing how to document, film, and position vessels to contest Chinese presences without provoking escalation. This is painstaking, slow, and under-reported work. Yet it is where the real defence of Scarborough is being fought — not in equipment transfers, but in the AFP's institutional capacity to durably and non-escalatorily contest Chinese presence in its exclusive economic zone.

Conclusion: Does the Alliance Actually Mean Something at Scarborough?

What the American Alliance Actually Provides

The American-Philippine alliance is not a shield against every Chinese maneuver in disputed waters — it never claimed to be. Its value is strategic and deterrent: it signals to Beijing that an open act of aggression against the Philippines would trigger an American response far exceeding Philippine capabilities alone. That deterrence has functioned since 2012 by keeping Scarborough in a grey zone rather than an open Chinese military base — despite the constant presence of Chinese vessels harassing Philippine fishermen.

Its Real Limits Against Chinese Grey-Zone Tactics

But against grey-zone tactics — scientific platforms, water cannons, floating barriers — the American alliance offers no calibrated and credible response. That is the challenge Washington must address: developing a response spectrum between "do nothing" and "direct military intervention" to contest incremental Chinese advances without triggering uncontrolled escalation. The Triton drones are a step in that direction — insufficient, but in the right direction. What Manila truly needs is an American alliance that engages Beijing in grey zones with the same tactical creativity that China uses to create them.

Signed Maxime Marquette, columnist

Columnist's transparency box

My Position on China and the Indo-Pacific

I consider China the principal strategic threat to the liberal international order, and its South China Sea claims a flagrant violation of international law that democracies cannot accept without undermining themselves. I am in favour of the American-Philippine alliance and its strengthening. I nonetheless acknowledge the real limits of what Washington can and will do in grey zones — and I think that candour is necessary for an honest strategic debate.

Uncertainties in This Dossier

Beijing's real intentions regarding Scarborough remain difficult to assess precisely from the outside: is the goal a permanent base, or simply maintaining a pressure state without crossing the line? Assessments of Philippine capabilities and the details of American-Philippine strategic discussions are partially inaccessible to me. I worked on the basis of quality open sources — ISW, Washington Times, Asia Times, Eurasia Review — triangulating their information.

Sources

Primary sources

Washington Times — Tensions rise at disputed South China Sea shoal — June 25, 2026

ISW — China Taiwan Update, June 26, 2026 — June 26, 2026

Straits Times — US gives Philippines underwater vehicles as China feud persists — June 23, 2026

Secondary sources

Asia Times — China tests Scarborough as Manila casts beyond US for help — June 26, 2026

Eurasia Review — China's New Structure at Scarborough Reef Sparks Alarm — June 22, 2026

CLAWS — China's Floating Platform at Scarborough Shoal: A Pattern of Pressure — June 22, 2026