On September 28, 2026, the Philippine Coast Guard (PCG) announced that it had confirmed the Chinese survey ship Jia Hai Ke 7 (嘉海科7) was loitering about 38 nautical miles (about 70 km) northwest of Itbayat Island in Batanes province. The ship's Automatic Identification System (AIS) recorded a physically impossible track: after leaving Xiamen, China, at 12:59 a.m. on September 21, it appeared at 8:10 p.m. the same day off Papua New Guinea, roughly 2,000 nautical miles away. The PCG concluded that the position data was deliberately spoofed and voiced concern about activity near waters where undersea communications cables run through the Luzon Strait.
However, the information made public as of October 3 does not include evidence that the ship collected data on undersea cables or dropped observation equipment into the sea. When the Philippine Department of Foreign Affairs protested to China, it relied not on provisions protecting undersea cables but on Article 246 of the UN Convention on the Law of the Sea (UNCLOS), which requires a coastal state's consent for marine scientific research in its exclusive economic zone (EEZ). In this case, it is necessary to distinguish between what the ship was actually observed doing and inferences about its purpose.
Four days from suspected AIS spoofing to departure: the Chinese survey ship off Batanes
The trigger was Jia Hai Ke 7's anomalous AIS track. According to the explanation of PCG spokesperson Jay Tarriela, as reported by Taiwan's Central News Agency (CNA), the ship was recorded as leaving Xiamen at 12:59 a.m. on September 21, yet about 19 hours later it was transmitting its position from waters off Papua New Guinea. At 6:55 a.m. on September 28, it appeared near Itbayat Island in the northern Philippines. By contrast, a track compiled by the South China Morning Post (SCMP) from MarineTraffic data puts the Xiamen departure on September 19 and the arrival near Itbayat on September 22, which does not match the PCG's record. Because both are based on AIS data suspected of spoofing, the actual departure and arrival dates cannot be established.
AIS is a system in which vessels broadcast their own position, course and other information; if the transmitted data is altered, the ship can appear to be somewhere it is not. The PCG says it detected the ship from its monitoring station on Itbayat Island and then confirmed its position by cross-checking against Canada-provided "Dark Vessel Detection (DVD)" system. DVD is a system that uses satellite data to detect vessels, including those not transmitting AIS. Because the AIS track did not match independent surveillance information, the PCG concluded the ship had deliberately falsified its position.
The PCG's September 28 statement placed the ship 37.84 nautical miles northwest of Itbayat Island. In these waters, about 160 km from Taiwan, the ship did not hold a steady course and stayed in roughly the same place. It also did not respond to radio challenges from a PCG aircraft. The PCG argues that this behavior was consistent with a vessel conducting marine scientific research rather than simply passing through.
Things moved on October 1. According to the PCG announcement, at 7:55 a.m. the 97-meter large patrol vessel BRP Teresa Magbanua closed to within about 91 m of Jia Hai Ke 7. A rigid-hulled boat launched from the patrol vessel circled the survey ship and repeatedly issued radio challenges, while an Islander aircraft flying from Basco airport joined in monitoring from above. The PCG says the ship repeatedly took evasive action.
A China Coast Guard vessel with hull number 2503 then appeared and approached Teresa Magbanua while repeatedly issuing radio warnings. The PCG side kept a distance of about 914 m while shadowing. According to Tarriela, the PCG had initially considered boarding and inspecting Jia Hai Ke 7, judging that the privately owned ship did not enjoy sovereign immunity as a government vessel. He also said the China Coast Guard ship's escort of a civilian survey vessel was significant.
At 11:42 a.m., Jia Hai Ke 7 began moving from its loitering position at about 4.6 knots (8.5 km/h). In a statement, the PCG said that ordinary transit would involve a steady course, and claimed that staying in the same waters for four days strongly suggested marine scientific research. Teresa Magbanua continued to shadow the ship to near the outer edge of the EEZ, and on October 2 two China Coast Guard vessels were also accompanying it. Three Taiwan Coast Guard Administration patrol vessels were also deployed in the same waters, but Tarriela said there was no coordination with the Taiwanese side.
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Note that the PCG's "four days" counts calendar dates from September 28 to October 1. From 6:55 a.m. on September 28 to 11:42 a.m. on October 1 is actually about three days and five hours, and Tarriela himself said the ship was stationary for "almost three days." The Philippine foreign ministry rejected China's position on the basis of Article 246 of UNCLOS on October 2, and a suspicion that the ship had dropped equipment was publicly mentioned on October 3.
What the PCG has confirmed, and the allegations without evidence
The PCG's concern is what Jia Hai Ke 7 was investigating in these waters and what the collected data might be used for. Its September 28 statement said that continuing to loiter while spoofing AIS position data raises serious concerns about the security of undersea communications infrastructure and the military use of collected data. However, according to the Philippine newspaper Inquirer, the PCG has not presented evidence on what specific data the ship collected near the cable routes, or whether it collected any data at all.
On October 3, Tarriela said he suspected Jia Hai Ke 7 of dropping some kind of observation equipment. But the type and purpose of the equipment were not identified, and there was no explanation that the PCG had directly witnessed a drop or recovered any equipment. As for any relation to communications disruptions reported in Metro Manila and Central Luzon, he has not confirmed a link and said it was only speculation.
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Breaking down the information published as of October 3 by each party's claim and its basis gives the following.
| Claim / allegation | Claimed by | Published basis / status |
|---|---|---|
| Spoofed AIS position data | PCG | Anomalous AIS track showing more than 2,000 nautical miles traveled in about 19 hours, cross-checked against independent surveillance information |
| Conducted marine scientific research in the same waters | PCG | Behavior of not holding a steady course and loitering from September 28 to October 1 |
| Collected data in waters where cables are laid | Concern raised by PCG | No evidence published on whether or what data was collected |
| Dropped observation equipment into the sea | PCG spokesperson Tarriela | No information published identifying equipment, witnessing a drop, or recovering anything |
| Involved in communications disruptions in Metro Manila and elsewhere | PCG has not confirmed a link | No evidence of a link |
| Was conducting ordinary survey activity in waters under Chinese jurisdiction | Chinese Embassy in Manila | A legal claim about China's maritime rights and interests; separate from evidence of what the survey involved |
| Suspected of unauthorized marine scientific research in the Philippine EEZ | Philippine Department of Foreign Affairs | China did not apply for permission for the research, and the Philippines has not given consent |
Thus, what can be confirmed from public information is the anomalous AIS track and loitering, the lack of response to radio calls, and the responses of both countries' patrol vessels. The judgment that the ship was conducting marine scientific research is an inference based on the ship's behavior, and suspicions of data collection or equipment drops would need more concrete support. That said, this does not rule out the possibility that the PCG holds non-public surveillance information.
Jia Hai Ke 7's equipment is also important in considering these suspicions. According to a vessel profile published by Baird Maritime in May 2025, the ship is 70.26 m long with a displacement of 2,000 tonnes and is equipped with a Kongsberg DP2-class dynamic positioning system. DP2 is a redundant system designed to keep a vessel in position even if part of the equipment fails, and can be used for cable laying, geological drilling to water depths of 150 m, and tracking of underwater targets. The hull also has a 2.8 m-square opening called a moon pool, which allows observation equipment to be deployed and recovered. China Classification Society (CCS) describes the ship as China's first privately owned research vessel equipped with DP2, and it entered service in April 2025.
However, carrying such equipment is not evidence that it was actually used on this voyage. Tarriela explained that acoustic sounding, used in some marine scientific research, could be disrupted by noise from PCG patrol vessels, but the specific research being conducted has not been disclosed.
Concerns about undersea cables also need to be distinguished from actual damage incidents. According to the International Cable Protection Committee (ICPC), about 150 to 200 faults occur each year in the world's undersea communications cables, and 70 to 80% of them are caused by accidental damage from fishing activity, ship anchors and the like. No cable damage has been reported in the Jia Hai Ke 7 case, so at this stage it must be treated as suspicion about survey activity.
UNCLOS Article 246, the basis cited by the Philippine foreign ministry
On October 2, the Philippine Department of Foreign Affairs issued a statement strongly rejecting the Chinese Embassy's claims about maritime rights. The department said Jia Hai Ke 7 was operating within the Philippine EEZ and pointed out that under Article 246 of UNCLOS, a coastal state's consent is required to conduct marine scientific research in the EEZ and on the continental shelf. It said China had submitted no application for permission for the research and that the Philippines had given consent to no Chinese vessel, and argued that the PCG's response was lawful and ordinary law enforcement activity.
Notably, the department relied not on a provision directly governing protection of undersea cables but on the consent regime for marine scientific research. The department did not explain why it chose that provision, but it shows that the Philippines is treating the matter not as cable damage but as suspected unauthorized survey activity.
Checking the original text of UNCLOS, the relevant provisions can be organized as follows.
| Article | Main provision | Mention by the parties in this case |
|---|---|---|
| Article 58(1) | Freedom of other states to navigate and to lay submarine cables and pipelines in the EEZ | Not directly mentioned in the statements that can be verified |
| Article 79(2) | Reserves the coastal state's right to take reasonable measures, while prohibiting undue impediment to the laying and maintenance of cables on the continental shelf | Same |
| Article 113 | Requires states to adopt laws punishing the breaking of submarine cables through willful or culpably negligent acts | Same |
| Articles 56(1)(b)(ii) and 246(2) | Coastal state jurisdiction and consent regime for marine scientific research in the EEZ and on the continental shelf | Philippine Department of Foreign Affairs explicitly cited Article 246 |
| Article 248 | Requires states or others planning marine scientific research to provide detailed information at least six months before the expected start date | Not directly mentioned |
| Articles 74 and 83 | Provisions on delimitation of the EEZ and continental shelf | Mentioned by the Chinese Embassy in Manila |
The consent regime for marine scientific research and the provisions protecting undersea cables regulate different things. Articles 246 and 248 require, in principle, that states and others planning research in a coastal state's EEZ or on its continental shelf obtain prior consent and provide the research plan at least six months before the expected start date. It is a mechanism for informing the coastal state of the research's purpose and methods, the vessels and equipment to be used, and the areas where it will take place. By contrast, Articles 58 and 79 guarantee the freedom to lay and maintain submarine cables and do not directly govern the response to unauthorized marine scientific research.
Article 113 requires states to adopt laws to punish acts by ships or persons under their jurisdiction that willfully or through culpable negligence break a submarine cable beneath the high seas in a way that may interrupt communications. Under Article 58(2), certain high seas provisions, including Article 113, also apply to the EEZ insofar as they are compatible with the EEZ provisions. These articles themselves, however, do not set out concrete procedures allowing a coastal state to board and inspect foreign vessels or order them to leave.
China, for its part, disputes jurisdiction over the waters themselves. Guo Wei, deputy spokesperson of the Chinese Embassy in Manila, claimed that Jia Hai Ke 7 was conducting ordinary activity in waters under Chinese jurisdiction and complying with international law, including UNCLOS. He also criticized the PCG's response as harassment. The Chinese Communist Party-affiliated Global Times also described the ship's activity as lawful offshore marine geological survey work.
In response to the Philippine foreign ministry's rebuttal, the Chinese Embassy countered that the two countries' maritime claims overlap and should be resolved through negotiations under Articles 74 and 83. The Philippine side claims that unauthorized research took place in its own EEZ, while the Chinese side claims that its sovereign rights and jurisdiction extend to those waters. The question of whether consent was required is therefore tied to the conflict over maritime boundaries and jurisdiction.
There are also differing interpretations on distinguishing hydrographic survey from marine scientific research. Countries' views are not aligned on whether hydrographic surveys, which measure water depth and seabed topography, fall within the marine scientific research requiring consent under Article 246. According to Radio Free Asia (RFA), the United States stated in 2020 a position distinguishing hydrographic surveys, including those for military purposes, from marine scientific research. However, what kind of survey Jia Hai Ke 7 actually conducted has not been disclosed, and which legal category this activity falls into has not been determined.
What the Philippine government used in this response was not a provision requiring proof of damage to undersea cables but a system requiring prior consent for marine scientific research. At least in the foreign ministry's statement, proving that data collection or interference with cables actually occurred is not a premise of the protest.
In Taiwan, a ship captain was sentenced to three years in prison over a cable-cutting incident
A comparable case is the undersea communications cable cut in Taiwan in February 2025.
According to Taiwan's Central News Agency (CNA), on February 25, 2025, the Togo-flagged cargo ship Hong Tai 58 (宏泰58號) damaged the Taiwan–Penghu No. 3 undersea communications cable connecting the main island of Taiwan and Penghu. Chunghwa Telecom reported the cut, and after an investigation by Taiwanese authorities, the Tainan District Court on June 12 of that year sentenced the Chinese captain, surnamed Wang, to three years in prison for violating Article 72 of the Telecommunications Management Act.
中央社 CNA
In this case, there was concrete evidence linking the cable damage to the ship's actions. The site was designated a no-anchoring zone with multiple warning signs, and the cable's position was shown on the ship's electronic chart. According to the court, the captain gave the order to drop anchor, but the anchor was not properly secured to the seabed, and the ship dragged and severed the cable as it drifted in a zigzag. On this basis the court found intent.
The damages suffered by Chunghwa Telecom came to about NT$17 million in cable repair costs and about NT$1.8 million in ship agency fees. The seven crew members were not indicted for insufficient evidence and were repatriated. Subsequently, on August 29, 2025, the Tainan branch of the Taiwan High Court rejected the prosecution's appeal, and the three-year sentence was upheld.
The nature of the evidence and the legal response differ fundamentally between the Hong Tai 58 case and the Jia Hai Ke 7 case. In the former, the result of a cut cable was confirmed, and the captain's criminal liability was pursued under domestic law based on the electronic chart, the no-anchoring zone, the anchor's movements and other evidence. In the latter, no cable damage has been reported, and the basis published by the PCG mainly concerns the ship's position and behavior. No physical evidence has been presented about the purpose of the survey activity or whether equipment was dropped.
Taiwan had already suffered repeated undersea cable damage before this. According to the Taipei Times, Taiwan's communications regulator, the National Communications Commission (NCC), explained that the Taiwan–Matsu No. 2 cable was cut by a Chinese fishing boat on February 2, 2023, and the Taiwan–Matsu No. 3 cable by a cargo ship on the 8th of that month. According to Chunghwa Telecom, cables linking the main island of Taiwan and Matsu were damaged five times in 2021 and four times in 2022, with repairs costing NT$10 million to NT$20 million per cable. A 2.2 Gbps microwave link was also used as an alternative until service was restored.
Against the background of such damage, Taiwan has called for the protection of undersea cables as an international security issue. According to Reuters, at a seminar held in October 2026 by the US think tank Center for a New American Security (CNAS), Andrea Yang, Taiwan's deputy representative to the United States, referred to the case in which a Chinese captain was convicted. She argued that interference with undersea cables is an issue that should be taken up at the United Nations and that an international mechanism to prevent malicious acts needs to be considered.
The Philippines and Taiwan explore cooperation on protecting undersea cables, against the backdrop of Japan–Philippines maritime boundary talks
Following this incident, cooperation between the Philippines and Taiwan on protecting undersea cables is being considered.
On October 21 (US local time), Felipe Carino III, deputy chief of mission at the Philippine Embassy in the United States, revealed at the CNAS seminar that the Philippine government is exploring ways to deepen cooperation with Taiwan on undersea cable protection. According to Reuters, while maintaining its "one China policy," the Philippines believes it needs to advance practical cooperation to protect shared interests in the Bashi Channel, which lies between the two. The concrete measures cited were cooperation on sharing information and expertise and strengthening monitoring and response capabilities. Asked about the possibility of joint patrols, Carino said he was not aware of any specific plans.
In response, Chinese Foreign Ministry spokesperson Mao Ning warned the Philippines the next day, the 22nd, to strictly abide by the "one-China principle" in action. The Luzon Strait and the waters off Batanes are an important transit area for undersea communications cables linking the Philippines with Northeast Asia and other regions, and cooperation on protecting them could affect diplomatic relations with China.
Japan is also not unrelated to developments over maritime rights and interests in this region. In the joint statement issued with the May 28, 2026 Japan–Philippines leaders' meeting, Japan and the Philippines agreed to begin formal negotiations to delimit their maritime boundaries for the EEZ and continental shelf. The area covered is the sea east of Taiwan, and the two countries plan to clarify the boundary based on international law, including UNCLOS.
China has reacted strongly against these negotiations. China's Foreign Ministry claimed that the waters where Japan and the Philippines plan to delimit boundaries include China's EEZ and continental shelf, and criticized the move as infringing on China's maritime rights and interests. The Taiwanese side has also called for its own maritime rights not to be harmed by the negotiations. On June 3, Taiwan's Ministry of Foreign Affairs indicated it would seek confirmation from Japan and the Philippines that the negotiation process and agreed content would not affect Taiwan's rights. Taiwan also does not accept China asserting maritime rights on Taiwan's behalf.
Furthermore, at the end of June 2026, researchers from Chinese government-affiliated research institutions and universities held a symposium in Guangdong Province and expressed the view that the Batan Islands are Chinese territory. According to Kyodo News, the meeting, attended by researchers from Nanjing University, the Chinese Academy of Social Sciences and elsewhere, was held in objection to the agreement on Japan–Philippines maritime boundary talks. However, it is reported that the Chinese government has not been confirmed to have officially claimed sovereignty over the Batan Islands themselves, and the Philippine government has rebutted the researchers' views as groundless.
The Chinese Embassy's claim regarding Jia Hai Ke 7 also concerns sovereign rights and jurisdiction in the surrounding waters, not sovereignty over the Batan Islands. A claim to sovereignty over islands and a claim to rights and interests in the surrounding EEZ and continental shelf need to be treated separately.
What to watch: evidence of observation equipment and concrete cable-protection cooperation
The basis the Philippine government used in this case was suspicion of unauthorized marine scientific research in the EEZ. It protested on the grounds that China had submitted no application for research permission and that the Philippines had not given consent, and it did not take the form of proving cable damage or data collection. By contrast, in Taiwan's Hong Tai 58 case, the captain's individual criminal liability was pursued based on physical evidence, including the actual cable cut and the movement of the anchor. Even among problems involving the same undersea communications infrastructure, the evidence required and the legal means applicable differ between the stage where survey activity is suspected and after damage has occurred.
Going forward, what will be important in judging Jia Hai Ke 7's activity is whether information supporting the PCG's suspected drop of observation equipment is made public. If the type of equipment, recovered items or observation records are presented, they would provide material to verify what the ship was actually doing. Also worth watching is whether the information sharing and capacity building being considered by the Philippines and Taiwan lead to a concrete monitoring and protection regime in the Bashi Channel. The relationship between the maritime boundary negotiations China seeks under Articles 74 and 83 and the boundary delimitation talks proceeding between Japan and the Philippines will also remain an important issue.
On protecting undersea cables, the Taiwanese side is calling for an international mechanism at the United Nations, and the Philippine side is exploring practical cooperation with Taiwan. At present, however, neither means the establishment of a concrete joint monitoring regime or a new legal framework. On what evidence can countries respond to suspicious survey activity before any damage occurs? The Jia Hai Ke 7 case highlights how difficult that question is for the security of undersea communications infrastructure.