EDITORIAL: Beijing's grey-zone strategy in the South China Sea — a conquest without a declaration of war

Introduction: Beijing advances, without ever crossing the line

A floating platform that speaks volumes

In June 2026, Philippine authorities published photographs of a new Chinese floating structure installed near Scarborough Shoal, an atoll claimed by both Beijing and Manila. The platform — approximately 28 square metres, equipped with a communications antenna — was small enough not to constitute a permanent military base, yet visible enough to trigger a diplomatic alarm. It was removed after a few days. But the message had been sent.

"If this is the precursor to a more permanent presence, or the precursor to another malicious activity, it is concerning," declared Philippine Defence Secretary Gilberto Teodoro Jr to the Wall Street Journal. China, for its part, claimed it was a "temporary scientific installation to study coral reefs." This dissonance between what Beijing is actually doing and what it claims to be doing is nothing new — it is the very definition of grey-zone strategy: advancing without ever officially crossing the threshold of armed conflict, creating facts on the ground, then denying.

What the South China Sea represents

The South China Sea is one of the world's most important maritime routes: approximately $3 to $5 trillion in global trade transits through it each year. It is bordered by the Philippines, Vietnam, Malaysia, Brunei, Taiwan, and Hainan Island. China claims approximately 90% of its surface area under its "nine-dash line" — a line the Permanent Court of Arbitration declared illegal under international law in 2016 — a ruling Beijing simply ignored.

The grey-zone toolkit: Beijing's instruments

Fishing militias: the invisible army

The first instrument of China's grey-zone strategy is the maritime militia — fleets of officially civilian fishing boats, but coordinated and sometimes commanded by Chinese military structures. These vessels occupy claimed spaces, harass foreign fishermen, and create a permanent presence that makes any counter-move difficult without risking escalation. As early as 2021, more than 200 military vessels disguised as fishing boats had massed around Whitsun Reef. In 2026, the same pattern continues near Scarborough.

The logic is airtight: if Manila or Washington respond with military vessels to fishing boats, Beijing can accuse them of "provocation." If nobody responds, Beijing consolidates its presence. This is the grey-zone trap — it creates an asymmetry of response that favours the aggressor.

Water cannons and coercion below the lethal force threshold

The second instrument is the use of water cannons against Philippine resupply vessels headed to Second Thomas Shoal, where the Philippines maintains a military presence on a deliberately grounded warship, the BRP Sierra Madre. Chinese coast guard vessels have used water cannons to block resupply operations — a form of coercion that causes material and physical damage without deploying lethal weapons. Washington protested, invoked the US-Philippine mutual defence treaty, but has not sent warships to permanently escort resupply missions.

Artificial islands: militarisation presented as sovereign right

Seven reefs transformed into military bases

Between 2013 and 2015, China built seven artificial islands on reefs it claims in the Spratly Islands. These islands — Fiery Cross, Mischief Reef, Subi Reef, and four others — were equipped with three-kilometre-long runways, combat aircraft hangars, surface-to-air and anti-ship missile systems, and electronic warfare systems. In 2015, President Xi Jinping had promised President Obama that he would not militarise these islands. That promise was systematically broken.

These bases now constitute a permanent network of military power projection covering the entire South China Sea. They allow China to deploy combat aircraft, drones, and short-range submarines throughout the region — dramatically reducing the reaction window for littoral states and for the American military based in Guam.

UNCLOS ignored, international law under pressure

The 2016 ruling by the Hague Arbitral Tribunal found that Chinese claims over the South China Sea are illegal under the United Nations Convention on the Law of the Sea (UNCLOS). China simply refused to recognise the ruling. This refusal had no substantial consequences: no sanctions, no change in behaviour. This illustrates a fundamental limit of international law: it only applies when great powers accept to submit to it.

The economic dimension: controlling resources, not just territory

Hydrocarbons and fisheries as the real stakes

The South China Sea holds estimated reserves of 125 billion barrels of oil and 500 trillion cubic feet of natural gas, according to American estimates — though figures vary by source. Its waters provide fish stocks for hundreds of millions of people in the region. China's grey-zone strategy aims in part to monopolise access to these resources: by harassing Philippine, Vietnamese, and Indonesian fishing boats, by placing obstacles to foreign oil drilling in claimed zones, Beijing seeks to appropriate the economic wealth of these waters without assuming the costs of open war.

The Chinese narrative that presents this behaviour as "defence of national sovereignty" is particularly cynical: these claims have no legally recognised basis under international law, as the Hague tribunal confirmed. But in official Chinese communications — and in those of many countries dependent on Chinese investment — this narrative is rarely challenged head-on.

Economic pressure on littoral states

The Philippines, Vietnam, Malaysia, and Indonesia face a permanent dilemma: challenge Chinese incursions, risking the loss of investments, trade links, and economic partnerships with Beijing, or accept a status quo that progressively reduces their maritime sovereignty. This economic dependence as a lever of political pressure is precisely what grey-zone strategy exploits — littoral states know that confrontation has an immediate economic cost, while capitulation seems to have only long-term costs.

The international response: between principles and pragmatism

What the United States and its allies are doing

The United States maintains an active naval presence in the South China Sea through freedom of navigation operations (FONOPs), regularly sending warships through waters claimed by China to assert their international character. These operations have symbolic and legal value, but their impact on Chinese behaviour is limited. Mutual defence agreements with the Philippines, Japan, and Australia theoretically reinforce deterrence, but precise red lines are never clearly defined — leaving an ambiguity that Beijing exploits.

In June 2026, the Scarborough incident triggered a collective response: according to Eurasia Review, littoral countries coordinated a joint diplomatic response to the Chinese floating platform. This sign of regional cohesion against grey-zone strategy is encouraging. But diplomatic cohesion does not replace a clear doctrine on what constitutes a casus belli for the United States' allies.

The role of ASEAN and its limits

The ASEAN (Association of Southeast Asian Nations) is paralysed by its consensus principle and the presence within it of countries like Cambodia and Laos, heavily dependent on Chinese investment. The South China Sea Code of Conduct, negotiated for more than a decade between Beijing and ASEAN, has still not been finalised — and negotiations advance at a pace dictated by China. This institutional deadlock leaves grey-zone strategy free rein.

International law and its limits in the face of grey-zone strategy

The 2016 arbitration ruling: a legal victory without an enforcement mechanism

In July 2016, the Hague Arbitral Tribunal, seized by the Philippines, issued a historic ruling: the nine-dash line claimed by China is "without legal basis" under international maritime law (UNCLOS). China responded by describing the ruling as "null and void," refusing to recognise it. This ruling illustrates the fundamental limit of international law: there are mechanisms to determine rights, but no coercive mechanism to force great powers to comply when they decide to ignore it.

Since 2016, China has continued building artificial islands, militarising reefs, intercepting Philippine resupply vessels, and installing floating platforms in disputed zones — all while officially maintaining that it "respects international law." This dissonance between words and actions is characteristic of grey-zone strategy: violating international norms while maintaining a façade of legality. ASEAN, the Southeast Asian regional organisation, has been unable to produce a collective response given the economic interests of its members with China that paralyse consensus.

The Philippine response: from peaceful state to regional resistance actor

Manila refuses capitulation and seeks allies

The Philippines have transformed their posture toward China in recent years. Under the previous Rodrigo Duterte administration, Manila adopted a policy of accommodation with Beijing. Since then, the Philippine government has clearly chosen a different path: firm diplomatic resistance, recourse to international courts, and strengthening security alliances. The enhanced defence agreement with the United States (EDCA) allows the pre-positioning of American forces in several Philippine bases. Joint military exercises with the United States, Japan, Australia, and India are multiplying.

Faced with the Chinese floating platform at Scarborough Shoal in June 2026, the Philippine response was swift: photographs published immediately, firm official statements, mobilisation of regional allies. According to Eurasia Review, the Philippines, Japan, Australia, and other countries coordinated a collective response to this new incursion. This regional solidarity is precisely what grey-zone strategy seeks to prevent — isolating each victim to avoid coordinated pushback. That Manila succeeded in building this coalition, even partially, represents a diplomatic success.

Taiwan: the stakes beyond the South China Sea

Why grey-zone strategy in the South China Sea prefigures that toward Taiwan

Taiwan is watching what unfolds in the South China Sea with the greatest attention. The Chinese regime uses the same tools — progressively imposed air exclusion zones, military exercises in the Taiwan Strait, repeated intrusions into Taiwan's Air Defence Identification Zone (ADIZ) — to test the limits of Taiwanese resistance and American responses. The grey-zone strategy tested against the Philippines and Vietnam is, according to many analysts, a dress rehearsal for applying the same method to Taiwan — but at an incomparably greater scale and with incomparably higher stakes.

The takeover of Taiwan by force — or its capitulation under sufficiently intense grey pressure — would represent a first-order geopolitical shift: the loss of a democratic bastion, China's control over 60% of global advanced semiconductor production (notably at TSMC), and a signal that grey-zone strategy can defeat democracies without a single bullet fired. This is why the South China Sea is not a peripheral regional problem — it is a test of the global security architecture.

Conclusion: The urgency of a coherent response doctrine

Recognising the strategy to better respond to it

The first condition for an effective response to China's grey-zone strategy is to name it correctly. This is not "normal strategic competition" — it is progressive annexation by unconventional means. Affected states must develop a response doctrine covering the full spectrum: counter-maritime militias, permanent naval escorts for resupply missions, coordinated diplomatic support, but also targeted economic sanctions when lines are crossed.

What the West must understand

The South China Sea is not a purely Asian problem. The maritime routes that cross it feed European and American economies. The precedent set by China's grey-zone strategy — that international law can be ignored without real consequences — is a threat to the entire world order. Responding to China in the South China Sea means defending the principle that rules apply to everyone — including great powers.

Signed Maxime Marquette, columnist

Columnist's transparency box

My declared biases

I am pro-Western and believe that the rules-based international order, despite its imperfections, is preferable to a world dominated by powers that ignore international law at their convenience. This bias influences my treatment of the China question. My analysis draws on public sources: Washington Times, Eurasia Review, Washington Post, Army Recognition, and analyses from American and European think-tanks.

What I don't know

I do not have access to confidential information on Chinese military doctrines in the South China Sea. Hydrocarbon reserve estimates vary significantly by source. The Scarborough platform was removed — I do not know whether this was a genuine diplomatic concession or a provisional tactical withdrawal.

Sources

Primary sources

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

Eurasia Review — China's New Structure At Scarborough Reef Sparks Alarm And Triggers Collective Response — June 22, 2026

Secondary sources

ISW — Iran Update Special Report, June 24, 2026 — June 25, 2026

Foreign Policy — Analysis of Chinese grey-zone strategy in the South China Sea — 2026

Al Jazeera — Regional security analysis — June 25, 2026

Kyiv Independent — Defence and international security — June 2026