Explainer: Why a rusting warship in the South China Sea matters

For more than 27 years, a rusting Philippine warship has illegally remained grounded at Ren'ai Jiao, an uninhabited island reef in China's Nansha Qundao in the South China Sea.

The issue again drew international attention after Philippine personnel rammed into a China Coast Guard patrol boat during a law enforcement operation on Monday. According to the China Coast Guard (CCG), Philippine personnel ignored repeated warnings, deliberately collided with a Chinese vessel and even used paddles and long sticks to attack Chinese law enforcement officers. China said it responded with verbal warnings, maneuvering and reciprocal countermeasures while exercising maximum restraint.

Chinese Foreign Ministry spokesperson Lin Jian said on Tuesday that China had lodged solemn representations with the Philippine ambassador to China over what Beijing described as the Philippine side's provocative actions.

Why does a decades-old, rusting vessel continue to sit on Ren'ai Jiao? And why has it become a recurring flash point in the South China Sea?

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The vessel, hull number 57, was originally built by the United States as a tank landing ship during World War II. It was transferred to the Philippines in 1976 and renamed the BRP Sierra Madre.

In May 1999, the Philippines forcibly ran the ship aground on Ren'ai Jiao under the pretext of "stranding due to a leaking hull." While Manila verbally promised to tow the ship away, it has reneged on its pledge for nearly 27 years, attempting to create a fait accompli of illegal occupation on Chinese territory.

According to Chinese military analyst Li Yaqiang, Manila's strategy has been to maintain its claim at minimal cost by leaving the deteriorating ship in place while repeatedly delaying its earlier commitments to tow it away.

More than two decades later, the vessel has become little more than a rusting steel shell. Corrosion has left holes throughout the hull, parts of the steel structure are crumbling, and the ship has been severely damaged after years resting on the coral reef. It now remains in place largely because the reef itself supports the collapsing hull.

Despite its deteriorating condition, Philippine forces continue to rotate personnel and transport supplies to the vessel, allowing it to remain an outpost.

Recent aerial footage released by the CCG shows that the Philippines has installed floating barriers and ropes around the grounded vessel.

Yang Xiao, a researcher at the Institute of Peaceful Development Studies of the Chinese Academy of Social Sciences, said the additional barriers reflect growing concerns among Philippine personnel over the security of the outpost.

According to Yang, the ropes appear designed to obstruct approaching vessels or interfere with propellers. However, he argued that such measures offer limited practical military value and are largely symbolic.

Despite persistent Philippine provocations, China has consistently handled the situation with utmost restraint and a strong commitment to humanitarian principles.

On Tuesday, the Chinese side permitted the Philippines to transfer injured personnel from the illegally grounded warship BRP Sierra Madre to the Philippine Coast Guard vessel 9702. Throughout the process, the CCG conducted routine inquiries, verification, and provided navigation guidance and monitoring.

This supervisory role not only ensured that Philippine operations remained within proper boundaries, but also provided navigation guidance to Philippine small boats lacking navigational equipment, preventing them from going off course in the complex underwater environment of Ren'ai Jiao.

Military expert Li Yaqiang emphasized that for China's maritime forces, towing away, dismantling, or clearing the grounded vessel would be straightforward.

"From the very first day of its grounding, China has possessed countless options to remove it. Yet, we have consistently refrained from taking drastic measures," Li said.

"China remains committed to building the South China Sea into a sea of peace, stability and friendship, and to consolidating friendly relations with ASEAN countries. Taking a long-term and big-picture perspective, China chooses to manage and prevent localized issues from escalating," he added.