The Philippine Coast Guard (PCG) and the Chinese Embassy exchanged sharp statements on Friday following the detection of a Chinese research vessel operating near northern waters in the West Philippine Sea (WPS).

The PCG said it detected the Chinese Research Vessel (CRV) Tan Suo Er Hao approaching within approximately 19 nautical miles off the coast of Cagayan province using Canada’s Dark Vessel Detection program.

This detection of a Chinese ship followed by the deployment of a PCG Islander aircraft to conduct a Maritime Domain Awareness (MDA) flight to challenge the vessel’s presence, determine whether it was conducting marine scientific research without Philippine consent, and assert the country’s sovereign rights within its Exclusive Economic Zone (EEZ).

PCG spokesperson for the WPS, Commodore Jay Tarriela, said the operation was conducted in accordance with the Philippine Maritime Zones Act and the United Nations Convention on the Law of the Sea (UNCLOS), which require prior authorization for marine scientific research within a coastal state’s EEZ.

In response, Chinese Embassy deputy spokesperson Guo Wei defended the movement of a Chinese research vessel through the Luzon Strait, comparing it to travel on a “public highway permitted under international law.” 

“This is like driving on a public highway that international law clearly allows everyone to use—only to be accused of trespassing because someone insists a side road is the only 'approved' route,” Guo stressed. 

He said the strait, including the Bashi, Balintang, and Babuyan channels, remains open to international navigation under the United Nations Convention on the Law of the Sea (UNCLOS).

“The road didn’t suddenly stop being public just because one party says so,” Guo said, rejecting allegations that the vessel violated Philippine maritime rights. 

He also disputed PCG claims that there was no communication between a Chinese naval ship and a PCG vessel during a rescue of Filipino fisherfolk on 24 December, asserting that records and audio evidence exist.

Guo directly addressed Tarriela, urging him to “check the basic facts” before making accusations.

In response, Tarriela clarified that the PCG did not accuse the Chinese vessel of trespassing. 

Instead, he said the Coast Guard conducted a Maritime Domain Awareness (MDA) flight to challenge the vessel’s presence, determine whether it was conducting marine scientific research without Philippine consent, and assert the country’s sovereign rights within its Exclusive Economic Zone (EEZ).

“I never claimed that your Chinese research vessel ‘trespassed,’” Tarriela said, emphasizing that the PCG’s actions were consistent with UNCLOS and Philippine domestic law.

Tarriela further criticized what he described as China’s selective invocation of UNCLOS, accusing Beijing of ignoring provisions that contradict its expansive claims in the South China Sea. 

He also alleged that Chinese vessels have previously conducted marine scientific research within other countries’ EEZs without authorization.

Addressing Guo’s claim of coordination during the Dec. 24 rescue incident, Tarriela said genuine prior coordination would have involved the PCG National Headquarters, which serves as the country’s search-and-rescue center. 

He added that the PCG vessel was already in the area when the alleged communication occurred, noting that the timing raised questions about China’s narrative of humanitarian coordination.

“The PCG vessel was already deployed and in the vicinity when the call was made and recorded—actions that appear timed to bolster a narrative rather than reflect genuine, proactive humanitarian intent,” he emphasized.

Despite this, Tarriela said he welcomed public discussion of maritime incidents and expressed hope that Chinese officials would maintain the same openness when addressing what he described as illegal and aggressive actions by Chinese maritime forces. 

“I appreciate your openness in discussing matters publicly. I hope you will continue this approach to engagement even when addressing incidents that involve the barbaric, illegal, coercive, aggressive, and deceptive behavior of PRC’s maritime forces,” Tarriela told Guo.

The CRV Tan Suo Er Hao, an 87.25-meter advanced deep-sea scientific research vessel operated by the Institute of Deep-sea Science and Engineering under the Chinese Academy of Sciences, serves as a mothership for manned and unmanned deep-sea submersibles and supports comprehensive deep-sea operations.

Tarriela said the PCG monitoring indicated that the vessel departed from Hainan province in China earlier this month and transited through the western Philippine EEZ.

During the MDA flight, the PCG aircraft sighted the CRV heading eastward at coordinates Latitude 18°34.021′ N, Longitude 123°17.042′ E, approximately 55.78 nautical miles east of Santa Ana, Cagayan.

“The PCG pilot issued multiple radio challenges to the vessel, inquiring about its intentions and reminding it of the requirement for prior consent for marine scientific research in Philippine waters,”Tarriela asserted, noting that the CRV Tan Suo Er Hao "did not respond to any of the radio calls.”