The Philippine Coast Guard (PCG) flagged the presence of a Chinese research vessel detected off the coast of Cagayan in Northern Luzon on Tuesday, Dec. 30.

PCG spokesperson for West Philippine Sea (WPS) Commodore Jay Tarriela said the Chinese research vessel (CRV) “Tan Suo Er Hao” was spotted using Canada’s Dark Vessel Detection program within the country’s exclusive economic zone (EEZ).

In response, PCG Commandant Adm. Ronnie Gil Gavan ordered the immediate deployment of a PCG Islander aircraft to conduct a maritime domain awareness (MDA) flight and identify the vessel and determine its purpose.

The PCG said that the mission sought to verify whether the Chinese ship was conducting marine scientific research without Philippine consent. Such activity, according to Tarriela, would violate the Philippine Maritime Zones Act and the United Nations Convention on the Law of the Sea (UNCLOS).

During the patrol, the aircraft spotted the CRV Tan Suo Er Hao heading eastward about 55.78 nautical miles from 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. The CRV Tan Suo Er Hao did not respond to any of the radio calls,” Tarriela said.

The PCG said that the CRV Tan Suo Er Hao is an 87.25-meter deep-sea research vessel operated by the Chinese Academy of Sciences. It serves as a platform for manned and unmanned submersibles and supports deep-sea exploration missions.

Monitoring data showed the vessel departed from Sanya, Hainan province on Dec. 26. It passed through the western portion of the Philippine EEZ before moving toward the east.

Concerns have been raised in the past months about the presence of Chinese research vessels in Philippine waters, particularly in the WPS.

According to the PCG, more than two dozens of Chinese research vessels were monitored to have entered the Philippine EEZ this year.

Some of them were CRVs Song Hang and Dian Ke 1 Hao which were spotted off Palawan and Cagayan respectively in April; CRVs Tan Suo 3, Xiang Yang Hong 302, and Tan Suo Er Hao detected off Ilocos Norte and Palawan in May; CRV Xiang Yang Hong 05 seen off Cagayan in June; and CRVs Bei Diao 996, Xiang Yang Hong 10, and Zhuhai Yun monitored off Western Luzon in July.

“The Philippine Coast Guard remains vigilant in protecting the country’s maritime domain and will continue to monitor and challenge unauthorized activities within the Philippine EEZ in accordance with the directive of President Ferdinand Marcos, Jr. of upholding national sovereignty and maritime laws,” Tarriela said.