Russian Fishing Trawlers Tracked Loitering Over Transatlantic Undersea Cables More Than 500 Times

Russia appears to be using commercial fishing trawlers to map the undersea cables that connect the United States and Europe, according to an investigation by The Telegraph. The newspaper identified more than 500 incidents over a period of four and a half years in which Russian fishing boats loitered above critical communications cables.

The findings draw on data from Global Fishing Watch, which uses satellite information to follow vessels across the open ocean. The tracks of the suspect Russian ships were then compared against nautical charts that show where undersea cables lie.

Although most cable routes are broadly marked on charts so that ships can steer clear of them, any operation targeting the cables would require far more precise positioning data. The Telegraph pointed to three cases in which trawlers seemed to be surveying the infrastructure. One vessel traced the paths of nine separate cables beneath the Atlantic, among them the Atlantic Crossing 1 telecommunications cable and the decommissioned TAT-14, which was owned by Sprint Corporation. A second ship lingered near the transatlantic Hibernia Express cable before following the route of Shefa-2, which links Shetland with the Faroe Islands. A third partly followed the Amitie and Grace Hopper cables, which connect the UK, France and Spain to the US.

The vessels repeatedly slowed down, at times moving at only two to three knots. A senior naval officer told the paper that the ships under suspicion are large enough to carry an uncrewed surface vehicle or a remotely operated vehicle, and could deploy tethered units at very low speeds. "If you put a sonar-equipped ROV 100 meters above a feature of interest, you can map it with millimeter precision," the officer said. A NATO representative added: "We're absolutely aware of what Russian civilian fishing ships are up to and where .. Some of these ships have never seen a single fish on their deck."

The stakes are considerable. Undersea cables underpin the modern connected world, and an estimated $87 billion in economic activity passes through them. They would be among the first targets if a conflict between NATO and Russia were to break out. The trawlers are described as part of Russia's "gray-zone" warfare, in which the activities of commercial vessels cannot easily be traced back to the Kremlin.

Cable disruptions have already occurred in several parts of the world. In 2024, two cables, one linking Finland with Germany and another linking it with Estonia, were disrupted within a couple of months of each other. Taiwan detained a Chinese freighter suspected of severing a cable between its Penghu Islands and the main islands, and another Chinese ship has been suspected of cutting a cable connecting Taiwan to the US. More recently, NATO uncovered a Russian plot to sabotage the two largest undersea cables on Earth, a cable linking Australia and New Zealand with Indonesia and Singapore has been damaged, and Iran has threatened to cut cables passing through the Strait of Hormuz.

Protecting the cables is difficult. Their length makes constant patrols very hard, if not impossible, and most of their routes run through international waters, where vessels are generally free to pass over and map them. Navies do shadow questionable ships, but such behavior is typically not grounds for boarding, detention or seizure.