December 31, 2025 - The Philippine Coast Guard (PCG) has challenged the presence of a Chinese research vessel off the coast of Cagayan province, raising concerns about unauthorized activities within the country’s exclusive economic zone (EEZ).
According to PCG spokesperson for the West Philippine Sea Commodore Jay Tarriela, the vessel identified as Chinese Research Vessel (CRV) Tan Suo Er Hao was detected approximately 19 nautical miles off the Cagayan coast on December 30. The detection was made using Canada’s Dark Vessel Detection program, which tracks ships that may be operating without proper identification signals.
PCG Commandant Admiral Ronnie Gil Gavan immediately ordered the deployment of a PCG Islander aircraft to conduct a Maritime Domain Awareness (MDA) flight. The aircraft issued multiple radio challenges to the Chinese vessel, seeking clarification on whether it was conducting marine scientific research without Manila’s consent.
The PCG emphasized that such activity would be a violation of the Philippine Maritime Zones Act and the United Nations Convention on the Law of the Sea (UNCLOS).
The Tan Suo Er Hao is known as a deep-sea research vessel that serves as a base for submersible operations. Its presence so close to Philippine shores has heightened concerns about Beijing’s maritime activities in the northern Philippines, particularly given the vessel’s proximity to Taiwan and the broader regional security tensions.
“The PCG continues to assert the Philippines’ sovereign rights within its EEZ,” Tarriela said in a statement, underscoring the agency’s commitment to monitoring and challenging foreign vessels suspected of unauthorized operations.
The incident adds to a series of maritime encounters between Philippine authorities and Chinese vessels in recent years, reflecting ongoing disputes in the West Philippine Sea and adjacent waters. Analysts note that the northern Luzon coast, including Cagayan, has strategic importance due to its location facing Taiwan and the Pacific.
Research or Reconnaissance, the Philippines Must Stop Treating This as Routine
Another Chinese vessel appears near Philippine shores. Another challenge is issued. Another statement is released. And once again, Filipinos are left asking the same question. How many times must this happen before it stops being treated as routine?
Labeling the Tan Suo Er Hao as a “research vessel” does little to ease concern. In today’s geopolitical reality, research and reconnaissance often overlap. A deep-sea vessel operating just 19 nautical miles from Cagayan is not an innocent coincidence. It sits near Taiwan, along a strategic corridor, in waters where the Philippines has clear rights under international law.
What is troubling is not only China’s presence, but the predictability of the pattern. Enter Philippine waters. Test response. Gather data. Leave. Repeat. Each incident chips away at the idea that the EEZ is actively defended rather than merely monitored.
The Coast Guard did its job by challenging the vessel. But challenges alone are not deterrence. Repeated intrusions suggest Beijing calculates that consequences remain limited to radio calls and press releases.
Sovereignty is not asserted through documentation alone. It is asserted when violations carry cost, consistency, and consequence. If unauthorized vessels can approach this close without escalation beyond verbal challenges, the message sent is dangerous.
This is not about provoking conflict. It is about drawing firm lines and enforcing them. The Philippines cannot afford to normalize foreign vessels probing its waters under vague labels. At some point, vigilance must turn into resolve. Otherwise, presence becomes permission, and silence becomes surrender.
