Vessels Loiter Over Subsea Cables and Pipelines Across Five Theaters

What’s inside?

At a Glance

- Two Chinese state-linked vessels spent September running structured survey grids over separate transpacific subsea cable corridors, one around the Guam cable hub and one over the Japan to U.S. cables east of Japan.

- A third Chinese research vessel has been holding station in the Bashi Channel inside the Philippine EEZ since September 22 while spoofing its AIS position more than 2,000 nautical miles away, with its destination field reading “TOWING 1NM CABLE.”

- Two vessels are holding position over the Bab el-Mandeb cable corridor off Djibouti, one a Russia-linked bulk carrier loitering for more than eight days, the other a zombie identity spoofing its position for six weeks after departing the Houthi-held port of Hodeidah.

- Two sanctioned tankers that loaded at Primorsk a day apart ran matching 40- and 45-hour loiters over the FLAGS and Alwyn-Frigg gas pipelines feeding St Fergus, which supplies 25 to 50% of Britain’s gas.

- Two Russian-flagged tugs, one towing a barge fitted with a seabed-capable excavator, have spent a month over the Kattegat and Skagerrak cable corridors, prompting a Danish municipality to activate its crisis group.

- A Russian trawler with a documented IUU record has been working just outside Canada’s EEZ directly above five transatlantic cables since late August.

- Saudi terminals in the Middle East Gulf loaded 3,911 kbpd of crude between September 1 and 27, more than four times the August figure, with only four of 55 tankers calling with AIS on.

- Roughly 75 high-speed craft were observed swarming off Khasab on September 26, the largest swarm tracked since late June.

- Windward’s visual link analysis has connected 45 Russia-trading shadow fleet tankers to a single untraceable Hong Kong nominee director.

Chinese Survey Grids Converge on the Guam and Japan Cable Corridors

Two Chinese state-linked vessels have spent September running structured survey grids over separate transpacific subsea cable corridors, one around the Guam cable hub and one over the Japan to U.S. cables east of Japan.

A Chinese-flagged fishery patrol vessel operated by a state fishery research institute has run research-pattern grids on both sides of the Guam subsea cable hub for seven weeks. From August 31 to around September 20, it worked a grid east of Guam between the Bulikula and SEA-US cables. After crossing the Guam and CNMI EEZ between September 20 and 22, it began a second grid west of Guam in the Philippine Sea, still running as of September 29. From August 11 to 29, it had conducted similar activity next to the Philippine EEZ. On September 13, it met a Cook Islands-flagged tanker east of Guam for approximately six hours, likely to refuel. AIS has remained on throughout.

This is the first time the vessel has conducted this kind of activity in the region, having previously operated around China and occasionally in the Indian Ocean. The north-to-south legs and repeated slow-speed stops resemble a survey rather than a fishery patrol or a transit. Both grids sit on cable routes landing at Guam, the landing point for 11 subsea cables and a principal link between the U.S. and Asia. The activity fits a wider pattern of Chinese research vessels mapping the seabed around the Philippines, Guam, Hawaii and Wake.

The head of U.S. Naval Intelligence has said this data enables submarine navigation, concealment, and the positioning of seabed sensors or weapons. In mid-2025, a Chinese research vessel ran a comparable lawnmower mapping pattern just outside Guam’s EEZ for more than five weeks. A fishery patrol vessel draws less attention than a declared research ship, and its grids sit directly on the cable routes. Seven weeks of back-to-back activity, most of it around the Guam cable hub, supported by a tanker meeting that allows it to stay at sea, points to possible deliberate mapping of the seabed and cables around Guam.

Separately, a Chinese research vessel owned by a state university has been running a research grid east of Japan in the Northwest Pacific since September 11. Over 18 days, it made 27 low-speed research stops across an area crossed by the JUNO, Jupiter, FASTER, Topaz, Unity, PLCN, Pacific Crossing-1 and TGN-Pacific cables, which link Japan, Taiwan and the Philippines to the U.S. Its AIS stayed on throughout, and it is now heading southwest at 13 knots.

This is the vessel’s fourth trip to the same area since May 2024 and the first since November 2025. Each trip lasted 18 to 24 days and followed the same route through the Luzon Strait past Japan. Before 2024, the vessel worked mostly in the South China Sea. Returning to the same cable corridor every six to twelve months builds a multi-year record of the seabed and water conditions over these cables, which is the data needed to locate and reach them. A U.S. congressional commission report has warned that China is building dual-use capabilities to target transpacific cables.

A Research Vessel Spoofs Its Position Over the Luzon Strait Cables

A Chinese research vessel has been holding station in the Bashi Channel since 22 September, about 38 nm northwest of Itbayat, Batanes, inside the Philippine EEZ, while its AIS reports it somewhere else entirely.

The vessel left Xiamen on 19 September and sailed south past Taiwan into the strait. Windward data shows AIS spoofing and jamming around it while it loiters in a tight box over the cable routes, its reported track jumping between false positions while the ship itself appears to stay put. Its AIS destination field reads “TOWING 1NM CABLE.” The Philippine Coast Guard says the ship’s AIS placed it off Papua New Guinea, more than 2,000 nm away, that it ignored repeated radio challenges, and that the behavior is consistent with an unauthorized seabed survey.

The loitering box sits over the cables that run through the Luzon Strait: SEA-ME-WE 3, the China-US Cable Network, SJC, EAC-C2C, APCN-2 and the FLAG North Asia Loop, all of which also land in mainland China or Hong Kong. The same corridor carries cables that do not touch China at all: the TPU Taiwan–Philippines–U.S. system, in service since May 2026, and the planned AUG East linking Taiwan, the Philippines, Japan and Southeast Asia. Disrupting those would not affect Chinese traffic.

A vessel holding position over cable routes, concealing its location, and reporting a destination that reads like towed survey gear is consistent with seabed survey work, not transit or routine research. It fits a wider pattern of Chinese research-vessel activity around Taiwan since June, including operations near Taiwan’s undersea cables.

Windward’s MIOC fused AIS, spoofing and jamming detections, and cable-route data to place the vessel where its AIS said it was not. That is the purpose of all-source operational intelligence: establishing the actual position when the reported one is false.

Two Vessels Hold Position Over the Bab el-Mandeb Cable Corridor

An Antigua and Barbuda-flagged bulk carrier has been loitering at the Gulf of Aden approach to Bab el-Mandeb since September 16, off the coast of Djibouti above the India Europe Xpress, AAE-1 and SeaMeWe-5 cables, for more than eight days with no port call, ship-to-ship transfer or cargo activity. It broadcasts underway using engine at under 1 knot with its destination field set to armed guards onboard. The vessel carries a Windward Russia-related compliance flag dating to January 2026 and was re-registered in July 2026 under a new name, manager, and MMSI, its fourth MMSI and third name change since 2021.

The loiter box sits on the route of three cables, one of which was cut in February 2024 when a drifting ship dragged its anchor across the southern Red Sea seabed. Anchors and fishing gear cause most cable faults worldwide. The seabed here is approximately 268 to 1,380 meters deep, too deep for normal anchoring, which fits the vessel staying under power, but the shallower parts are within reach of a bulk carrier’s full anchor chain. Cables are usually buried only down to 1,000 to 1,500 meters, and below that lie exposed on the seabed. A recently re-registered, Russia-linked bulker holding position over this ground for over a week with no commercial activity has no clear reason to be there, and a single anchor let go in the shallower sections would be the same mechanism that cut cables in the area in 2024.

A second vessel, using the identity of a St Kitts and Nevis-flagged container ship reported dead since 2020, appeared on AIS on July 24 as it left Hodeidah, the Houthi-held port in Yemen. It called at Hodeidah twice more, between July 27 and 29 and between August 8 and 13. Since August 14, it has been spoofing its position, broadcasting a looping track in a tight box just off Djibouti directly over where AAE-1, SeaMeWe-5 and IEX approach their landing points. Across those 41 days, it has made no port calls and done no cargo work, with more than 20 AIS gaps, including a 40.5-hour dark period between September 8 and 10.

This comes as Iran has weighed attacks on Gulf undersea cables, while the Houthis have taken Mocha and islands near Bab el-Mandeb and have reportedly threatened to harm underwater telecommunications cables in the region over the past two years. A zombie vessel reappearing out of Hodeidah and then spoofing its location over one of the region’s main cable landing points for six weeks has no clear commercial explanation, and its Hodeidah origin points to a possible Houthi link.

Matching Loiters Over the Pipelines Feeding Britain’s Main Gas Terminal

Two crude tankers under UK and EU Russia sanctions, one Chinese-owned and one commercially controlled by a Russian state shipping company since July 12, 2026, loaded at Primorsk a day apart between September 16 and 18 and both declared Port Said as their destination.