China claims that the grounded Philippine warship is damaging marine life at Second Thomas Shoal and demands its removal.

China has formally accused the Philippines of allowing its deliberately grounded warship at Second Thomas Shoal to damage the surrounding marine environment, demanding the vessel’s removal as a necessary step to protect the ecosystem. The claim, which frames a long-standing territorial dispute through an environmental lens, adds a new dimension to a confrontation that has simmered for over two decades. For the Philippines, which views the rusting hull of the BRP Sierra Madre as a sovereign outpost, the accusation shifts the debate from geopolitics to ecological stewardship — a charge Manila denies.

The environmental argument is not entirely new — both sides have previously accused each other of harming the reef — but China’s recent formal demand for removal marks a notable escalation in rhetoric. The claim centres on the idea that the decaying warship, which has been exposed to seawater and corrosion for more than 25 years, is leaching pollutants into the waters of the Spratly Islands. Beijing argues that this violates the 2002 Declaration on the Conduct of Parties in the South China Sea (DOC), which commits signatories to refraining from inhabiting presently uninhabited features. The Philippines, for its part, maintains that the vessel is a legitimate military outpost and that any environmental impact is negligible compared to the damage caused by Chinese fishing and construction activities in the region. For a broader look at how pollution issues are being tackled across the country, see how government and NGOs are tackling pollution in the Philippines.

What the provisional arrangement actually allows — and what it doesn’t

At the heart of the dispute is a fundamental disagreement over what the provisional arrangement, reached in July 2024 after a near-catastrophic clash, actually means. The Philippines describes it as a “Provisional Understanding” that allows it to continue rotating personnel and delivering supplies to the marines stationed on the Sierra Madre. From the conclusion of that arrangement through March 4, 2026, Manila carried out 13 rotation and resupply missions — roughly once every six weeks — and Philippine officials say these have proceeded without dangerous encounters. China, however, insists that the arrangement is a transitional measure whose sole purpose is to pave the way for the vessel’s removal. The two sides also disagree on what constitutes a “basic living necessity.” For Manila, structural reinforcement materials are essential to keep the ship from collapsing; for Beijing, they are a prohibited expansion of military presence.

How the standoff nearly spun out of control — and what changed

The situation at Second Thomas Shoal came close to spiralling into open conflict in mid-2024. On June 17, the China Coast Guard (CCG) blocked a Philippine resupply mission, injuring eight Filipino sailors, one seriously. In the months leading up to that incident, Philippine supply boats had been rammed and shot with high-pressure water cannons, in some cases injuring crew members. The escalation was part of a broader pattern: China had been steadily increasing its maritime presence around the shoal, deploying CCG vessels, maritime militia boats, and even a helicopter and surveillance drone. The Armed Forces of the Philippines (AFP) reported that as of August 20, 2025, at least five CCG vessels, supported by 11 fast boats and nine militia vessels — some of which appeared to have been upgraded with mounted weapons — were operating in the vicinity.

The July 2024 arrangement de-escalated the immediate crisis, but it did not resolve the underlying dispute. The Philippines has not acknowledged any obligation to comply with conditions such as reporting resupply operations in advance, while China continues to insist on on-site inspections. Meanwhile, the Sierra Madre itself is deteriorating. Decades of corrosion and seawater exposure have taken a heavy toll, and the Philippine military faces an urgent need to bring in reinforcement materials just to keep the vessel habitable. This creates a structural tension: the longer the ship remains grounded, the more Manila needs to reinforce it, and the more Beijing sees that reinforcement as a violation of the arrangement. For a closer look at how pollution from industrial sources affects Filipino communities, read about pollution’s heavy toll on Filipino communities.

What the environmental claim reveals — and what it obscures

China’s accusation that the grounded warship is damaging marine life is worth examining on its own terms, but it also serves a strategic purpose. By framing the issue as an environmental violation, Beijing can argue that the Philippines is not only infringing on Chinese sovereignty but also violating the DOC’s commitment to environmental protection. The claim is difficult to verify independently, as access to the shoal is restricted. What is clear is that the Sierra Madre, an aging US-built landing ship, has been sitting on the reef for over 25 years. Its hull is rusting, and it is reasonable to assume that some amount of paint, metal, and fuel residue has leached into the surrounding water. However, the scale of that impact relative to other human activities in the area — such as Chinese fishing fleets and construction on other features — is not established in the available evidence.

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The environmental argument also obscures a more fundamental disagreement: what the shoal’s “natural” state should be. China insists that the feature should be uninhabited and without any facilities, a position rooted in the DOC. The Philippines, however, argues that its presence is a legitimate exercise of sovereignty over what it calls the Kalayaan Island Group. The Sierra Madre is not just a ship; it is a symbolic outpost that allows Manila to maintain a physical presence on a feature it claims. Removing it would be politically difficult for any Philippine administration. At the same time, the vessel’s continued deterioration means that the status quo is not stable. Eventually, the ship will become uninhabitable, and Manila will have to decide whether to build a permanent structure — which would almost certainly provoke a strong Chinese response — or withdraw. For more on how environmental issues are being addressed by younger generations, see youth activism tackling pollution in the Philippines.

The Scarborough Shoal collision: a separate but related flashpoint

While Second Thomas Shoal has been the focus of recent attention, another incident at Scarborough Shoal in August 2025 underscores the broader volatility of the South China Sea. According to the Philippine Coast Guard (PCG), a CCG vessel collided with a People’s Liberation Army Navy warship after the Chinese vessel undertook a “risky maneuver” while pursuing a PCG boat delivering supplies to Filipino fishermen. The collision resulted in substantial damage to the CCG vessel’s forecastle, rendering it unseaworthy. The incident, captured on video by the PCG, was highly embarrassing for the Chinese government, which has not officially acknowledged it. The episode illustrates how quickly a routine operation can escalate into a dangerous confrontation, and it reinforces the need for clear communication channels between the two sides.

What the Philippines can do — and what it cannot

For the Philippines, the options at Second Thomas Shoal are constrained by both diplomatic and practical realities. The provisional arrangement has provided a measure of stability, but it is not a permanent solution. Manila must navigate a narrow path between maintaining its presence and avoiding a confrontation that could trigger the U.S.-Philippines Mutual Defense Treaty — a scenario neither side appears to want.

Continue resupply under the existing terms

The most straightforward option is to keep doing what the Philippines has been doing: conducting rotation and resupply missions roughly every six weeks, delivering only basic living necessities. This approach has worked since July 2024, with no dangerous encounters reported. However, it does not address the long-term problem of the vessel’s deterioration. The Sierra Madre will eventually need structural reinforcement, and under the current arrangement, China is likely to oppose any attempt to bring in construction materials. Manila must decide whether to seek a renegotiation of the terms or accept that the ship’s lifespan is limited.

Reinforce the vessel — and risk escalation

If the Philippines decides that the Sierra Madre must be reinforced to remain habitable, it will almost certainly face Chinese opposition. Transporting large quantities of construction materials would be seen by Beijing as a violation of the provisional arrangement and an expansion of military presence. The risk of a confrontation similar to the June 2024 clash is high. The Philippines could attempt to reinforce the vessel under cover of a resupply mission, but this would likely be detected and could lead to a more serious incident. The United States has stated that the Mutual Defense Treaty applies to the South China Sea, but it is unclear whether Washington would intervene in a dispute over construction materials.

Negotiate a new arrangement

A third option is to pursue a diplomatic solution that addresses both sides’ core concerns. The Philippines could offer to limit the size and frequency of resupply missions in exchange for China’s agreement to allow limited structural reinforcement. Alternatively, Manila could propose a joint environmental assessment of the shoal, which might provide a neutral basis for discussing the vessel’s impact. However, any negotiation would require China to accept that the Sierra Madre will remain in place for the foreseeable future — something Beijing has so far been unwilling to do. For a deeper look at how solid waste management challenges are being addressed in the Philippines, read about addressing solid waste management in the Philippines.

Prepare for the vessel’s eventual collapse

The least discussed option is the one that may be most realistic: the Sierra Madre will eventually become uninhabitable due to corrosion, and the Philippines will have to withdraw. This would be a political setback, but it would also remove a source of tension. Manila could plan for an orderly withdrawal, perhaps by building a small, non-permanent structure on the shoal before the ship collapses. However, even this would likely be opposed by China, which insists that the feature should remain uninhabited. The Philippines would need to decide whether to make a stand on the shoal itself or to shift its focus to other features in the Kalayaan Island Group.

Frequently asked questions about the Second Thomas Shoal dispute

The Second Thomas Shoal dispute is unlikely to be resolved soon. The provisional arrangement has bought time, but it has not addressed the fundamental disagreement over sovereignty and the vessel’s status. For the Philippines, the immediate priority is to keep the Sierra Madre habitable without triggering a confrontation. For China, the goal remains the vessel’s removal. The environmental claim adds a new rhetorical layer, but it does not change the underlying calculus. What happens next will depend on whether both sides can find a way to manage the ambiguity of the current arrangement — or whether one side decides to force the issue. If this was useful, you might also want to read research uncovering serious plastic pollution issues in the Philippines.

Sources

Filipino cities choke on e-waste — A look at how electronic waste is affecting urban communities in the Philippines.

Toxic spill pollutes Filipino river — An examination of industrial pollution incidents and their impact on waterways.

Divergence and Tacit Understanding in the China-Philippines Provisional Arrangement at Second Thomas Shoal. Center for Strategic and International Studies, 2025.

Philippine Military Claims Increased Chinese Movements at Second Thomas Shoal. The Diplomat, August 2025.