Manila said it would send coast guard aircraft and vessels to challenge four Chinese research ships operating in waters where the Philippines says Beijing has no authority to conduct marine scientific work without consent.
The Philippine Coast Guard said the vessels were detected on Sunday in separate locations near Batanes, Palawan and the Scarborough Shoal area, sharpening an already tense maritime standoff between the two neighbours. Officials said the ships’ movements and equipment showed signs of oceanographic survey activity, including deep-sea research, acoustic mapping, geophysical work and unmanned systems deployment.
Coast Guard Commandant Admiral Ronnie Gil Gavan said the Philippines would not tolerate unauthorised marine scientific research in waters under Manila’s jurisdiction. The agency said the operations violated the United Nations Convention on the Law of the Sea because they lacked legal authority and prior approval from the Philippine government.
The ships identified by Manila include Xiangyanghong 33, Shi Yan 1, Jia Geng and Zhuhaiyun. Xiangyanghong 33 was reported about 140 nautical miles northwest of Rizal, Palawan, near Quirino Atoll. Shi Yan 1 was tracked around 118 nautical miles west of Itbayat, Batanes, while Jia Geng was seen about 88 nautical miles northeast of the same island municipality. Zhuhaiyun was reported more than 100 nautical miles northwest of Scarborough Shoal, also described as west of Bolinao, Pangasinan.
The presence of Zhuhaiyun is especially sensitive because it is designed as an intelligent drone mother ship capable of deploying dozens of unmanned aerial, surface and underwater vehicles. Such platforms can be used for scientific mapping, but their dual-use potential also raises security concerns in contested waters where seabed data, currents, bathymetry and acoustic conditions are relevant to naval operations.
China has long maintained sweeping claims over most of the South China Sea, including areas inside the Philippines’ 200-nautical-mile exclusive economic zone. Manila rejects those claims, citing the 2016 arbitral ruling that found Beijing’s expansive historic-rights claim had no legal basis under international law. China has refused to recognise the ruling and continues to assert sovereignty over reefs, shoals and maritime zones claimed by several Southeast Asian states.
Sunday’s dispute unfolded as Beijing separately accused Philippine personnel of landing on Sandy Cay, an unoccupied sandbar near Philippine-held Thitu Island in the Spratly chain. China’s coast guard said five Philippine personnel had entered what Beijing calls Tiexian Jiao, while Manila has insisted that its actions in the area are lawful and aimed at asserting jurisdiction.
The Sandy Cay friction follows an earlier episode in which Chinese coast guard personnel were shown on the sandbar holding a Chinese flag, prompting Manila to send its own coast guard and civilian-linked missions to the area. Sandy Cay lies close to Thitu Island, one of the most strategically important Philippine-held features in the Spratlys, where overlapping claims by China, the Philippines, Vietnam, Malaysia and Taiwan continue to drive patrols and counter-patrols.
The latest maritime encounter also comes during Balikatan 2026, the large annual military exercise involving the Philippines, the United States and other partners. More than 17,000 personnel are taking part in drills running from April 20 to May 8, with activities focused on coastal defence, live-fire training and joint operations near the South China Sea and Taiwan Strait. Beijing has criticised the exercises, while Manila says they are defensive and consistent with alliance commitments.
Marine scientific research has become a flashpoint because UNCLOS gives coastal states specific rights over research activity in their exclusive economic zones and continental shelves. Foreign ships may enjoy freedom of navigation, but research involving seabed mapping, data collection and survey equipment generally requires permission from the coastal state when conducted in an EEZ.
Manila has challenged similar Chinese research activity before. Last year, a Chinese research vessel was monitored in the Philippines’ exclusive economic zone off the northern Ilocos coast, prompting coast guard deployment and warnings that its movements were inconsistent with ordinary navigation. Philippine officials also reported seeing equipment linked to deep-sea research during that operation.
The Philippine Coast Guard said the vessels were detected on Sunday in separate locations near Batanes, Palawan and the Scarborough Shoal area, sharpening an already tense maritime standoff between the two neighbours. Officials said the ships’ movements and equipment showed signs of oceanographic survey activity, including deep-sea research, acoustic mapping, geophysical work and unmanned systems deployment.
Coast Guard Commandant Admiral Ronnie Gil Gavan said the Philippines would not tolerate unauthorised marine scientific research in waters under Manila’s jurisdiction. The agency said the operations violated the United Nations Convention on the Law of the Sea because they lacked legal authority and prior approval from the Philippine government.
The ships identified by Manila include Xiangyanghong 33, Shi Yan 1, Jia Geng and Zhuhaiyun. Xiangyanghong 33 was reported about 140 nautical miles northwest of Rizal, Palawan, near Quirino Atoll. Shi Yan 1 was tracked around 118 nautical miles west of Itbayat, Batanes, while Jia Geng was seen about 88 nautical miles northeast of the same island municipality. Zhuhaiyun was reported more than 100 nautical miles northwest of Scarborough Shoal, also described as west of Bolinao, Pangasinan.
The presence of Zhuhaiyun is especially sensitive because it is designed as an intelligent drone mother ship capable of deploying dozens of unmanned aerial, surface and underwater vehicles. Such platforms can be used for scientific mapping, but their dual-use potential also raises security concerns in contested waters where seabed data, currents, bathymetry and acoustic conditions are relevant to naval operations.
China has long maintained sweeping claims over most of the South China Sea, including areas inside the Philippines’ 200-nautical-mile exclusive economic zone. Manila rejects those claims, citing the 2016 arbitral ruling that found Beijing’s expansive historic-rights claim had no legal basis under international law. China has refused to recognise the ruling and continues to assert sovereignty over reefs, shoals and maritime zones claimed by several Southeast Asian states.
Sunday’s dispute unfolded as Beijing separately accused Philippine personnel of landing on Sandy Cay, an unoccupied sandbar near Philippine-held Thitu Island in the Spratly chain. China’s coast guard said five Philippine personnel had entered what Beijing calls Tiexian Jiao, while Manila has insisted that its actions in the area are lawful and aimed at asserting jurisdiction.
The Sandy Cay friction follows an earlier episode in which Chinese coast guard personnel were shown on the sandbar holding a Chinese flag, prompting Manila to send its own coast guard and civilian-linked missions to the area. Sandy Cay lies close to Thitu Island, one of the most strategically important Philippine-held features in the Spratlys, where overlapping claims by China, the Philippines, Vietnam, Malaysia and Taiwan continue to drive patrols and counter-patrols.
The latest maritime encounter also comes during Balikatan 2026, the large annual military exercise involving the Philippines, the United States and other partners. More than 17,000 personnel are taking part in drills running from April 20 to May 8, with activities focused on coastal defence, live-fire training and joint operations near the South China Sea and Taiwan Strait. Beijing has criticised the exercises, while Manila says they are defensive and consistent with alliance commitments.
Marine scientific research has become a flashpoint because UNCLOS gives coastal states specific rights over research activity in their exclusive economic zones and continental shelves. Foreign ships may enjoy freedom of navigation, but research involving seabed mapping, data collection and survey equipment generally requires permission from the coastal state when conducted in an EEZ.
Manila has challenged similar Chinese research activity before. Last year, a Chinese research vessel was monitored in the Philippines’ exclusive economic zone off the northern Ilocos coast, prompting coast guard deployment and warnings that its movements were inconsistent with ordinary navigation. Philippine officials also reported seeing equipment linked to deep-sea research during that operation.
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