Chinese research vessel spotted in Philippine Rise

MANILA, Philippines — A Chinese research boat was spotted operating illegally in the Philippines’ eastern waters, particularly in the potentially oil- and gas-rich Philippine (Benham) Rise.

Sealight, an independent maritime monitoring group headed by former US Air Force official and defense attaché Ray Powell, monitored the activities of Tan Suo Er Hao in Benham Rise and in the vicinity of Batanes within the Philippines’ exclusive economic zone (EEZ).

“China’s deep-sea research vessel Tan Suo Er Hao appears to be conducting unauthorized survey activity inside the #Philippines’ exclusive economic zone since (April 2),” Powell said on X.

Sealight said the 87.25-meter Chinese vessel departed Sanya Port on March 15 and its voyage “first took it into the Benham Rise area east of the Philippines, where it also encroached on the edge the Philippine EEZ as it conducted surveys from 21-31 March.”

“It then passed back through the Luzon Strait before briefly loitering 50 nautical miles from the Batanes Islands (also inside the Philippine EEZ) on April 1,” Sealight reported.

On Friday, the Chinese research vessel was monitored roughly 100 nautical miles from the nearest Philippine baseline around Babuyan Islands.

Sealight said the Tan Suo Er Hao is operated by the Chinese Academy of Sciences’ Institute of Deep-Sea Science and Engineering.

The vessel, the report said, serves as the mothership for China’s Fendouzhe and Shenhaiyongshi crewed submersibles.

“Its 13 onboard laboratories and full-ocean-depth geological winch give it significant deep-sea research and intelligence collection capability,” Sealight said.

Sealight noted that under Article 246 of the United Nations Convention on the Law of the Sea (UNCLOS), marine scientific research in the EEZ of a coastal state requires the latter’s “express consent.”

In December last year, the Philippine Coast Guard challenged the same research vessel after it was monitored conducting surveys within approximately 19 nautical miles off the coast of Cagayan province.

United front

Speaking at a forum on Tuesday organized by the Stratbase Institute and the Embassy of Japan, top Philippine security officials and maritime experts renewed their call for a united front in the West Philippine Sea as they pressed for diplomacy, transparency and tighter security partnerships to uphold the country’s 2016 arbitral victory over China.

The forum was held to mark the 70th anniversary of the normalization of diplomatic ties between the Philippines and Japan.

“In the face of the People’s Republic of China’s increasing assertiveness in the West Philippine Sea and the broader South China Sea, the Philippines remains firmly anchored in international law, diplomacy and transparency,” Armed Forces chief of staff Gen. Romeo Brawner Jr. said at the forum. He described the country’s posture as “principled restraint, coupled with resolve.”

He said the Philippines would continue to assert its maritime rights “through peaceful and lawful means,” citing the 2016 arbitral ruling under the UNCLOS that invalidated China’s sweeping claims in the South China Sea.

Brawner pointed to expanding defense cooperation with allies, including the “SQUAD” grouping and upcoming Balikatan exercises, which will include Japanese troops – a historic first – as proof of Manila’s resolve.

Stratbase Institute president Dindo Manhit said defending Philippine sovereignty requires a broader, multi-sectoral effort beyond government, underscoring the need for “strategic clarity” and stronger coordination with democratic partners “because the next 70 years will not be defined by history – but by how we act today.”

“In a region where the stakes continue to rise, the Philippines and Japan have both the opportunity and the responsibility to work together – to strengthen economic resilience, enhance security cooperation and uphold the principles that keep our region stable and open,” he maintained.

Retired Supreme Court justice Antonio Carpio, for his part, said enforcement of the 2016 Arbitral Award does not rely on a single global authority but on the continued presence of allied navies in contested waters.

“Every time the US and its allies sail in the West Philippine Sea … that is enforcement,” Carpio said, explaining that such operations affirm the area as part of the Philippines’ EEZ under the ruling.

He urged the government to pursue additional legal remedies, including new arbitral cases over overlapping extended continental shelf claims, to further strengthen the landmark decision and build international support.