On board the HMS St Albans there was complete silence in the darkened sonar room. Two dozen specialists watched over by Commander Matt Teale listened carefully for any seabed movement detected by an array of sonar buoys. These were towed behind the ship, dropped by its submarine-hunting Merlin helicopter and the RAF’s Poseidon marine patrol aircraft. Others had been placed in position by Britain’s Norwegian allies.
They found it. At a depth of around 2,000 metres, two Russian submarines were working close to a major internet cable in the approaches to the Greenland-Iceland-UK gap. According to the defence secretary, John Healey, they were conducting “malignant activity”. In other words, they were either actually cutting the cable or mapping the exact route and locating the vulnerable junctions so that they could easily destroy the link later.
There are an estimated 570 operational cables extending more than 1.5m kilometres along the seabed. Another 130 are due to start operating in the next few years. They carry 97% of the world’s internet traffic, including financial data and military communications.
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Recently, the AUKUS defence ministers announced that Britain, the US and Australia would jointly develop a fleet of submarine drones to patrol and protect the world’s undersea cables. The cost of about 200 such drones is estimated at $2.5bn, or about half the cost of one Virginia-class submarine, the backbone of America’s submarine fleet.
The promised drone subs are designed to constantly patrol the cable routes. They will look for and report on any Russian or Chinese submarine activity and damage – they know that if they are caught in the act, it will have political consequences.
Nato currently lags far behind the Russians in military seabed technology. Most of what they have is based on a cold war system known as SOSUS (Sound Surveillance System), a web of seabed hydrophones. SOSUS was designed to detect Soviet submarine movements, and some of the equipment remains in place and can be used to help protect some cables. But the network is now out of date, and 90% of the world’s cables have been laid since the end of the cold war.
A highly secretive branch of the Russian ministry of defence known as the Main Directorate of Deep-Sea Research (GUGI) is responsible for mapping undersea cables and sabotage work. Most of Russia’s information cables are land-based. GUGI operates about a dozen submarines and several surface vessels based at the Olenya Guba naval base on the Kola Peninsula.
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GUGI’s jewel in the crown is the Belgorod. Known as the “aircraft carrier of submarines”, it displaces 30,000 tons underwater, three times more than the Virginia-class sub. The Belgorod can operate at depths of up to 6,000 metres and carries manned mini subs that can be launched for detailed work.
The Ministry of Defence refuses to provide full details, but it is believed to have been the Belgorod that was detected earlier this year. It had already detached one of its mini submarines, the Losharik, with a highly specialised crew of 25.
The submarines are the pride of the Russian navy’s espionage fleet, but they also operate a number of surface vessels as part of their “grey” war on undersea cables. Chief among the surface craft is the Yantar.
The Yantar has been regularly sighted in the Channel and the North Sea. It operates in the Baltic, off Greenland and has even been seen in the waters between Cuba and Florida. The Yantar operates a multi-beam sonar, which creates three-dimensional maps of the seabed and is also equipped with drone submarines. The Russians also have dozens of ships in their naval hydrographic mapping division, which can be adapted for espionage work.
As well as plotting the exact locations of cables, the Russian espionage fleet is locating cable landing sites and their vulnerabilities. Since the start of the Ukraine war, security at cable landing sites has been substantially increased.
Russian undersea espionage increased extensively after the invasion of Ukraine. So did the actual sabotage. On Christmas Day 2024, the Russian shadow fleet tanker Eagle S dragged its anchor for 90km along the floor of the Baltic, cutting an electricity cable and four telecoms cables. The tanker was boarded and her captain arrested. But the case was dismissed by the Finnish court because the incident happened in international waters.
The Chinese conducted a similar operation in the Baltic, probably at the behest of the Russians. On November 17-18, 2024, the bulk carrier Yi Peng 3 dragged its anchor and cut two major telecoms cables between Finland and Estonia.
It is likely that Russian espionage vessels mapped the exact location of the cables so that the Eagle S and Yi Peng 3 knew where to drop their anchors to cause the most damage.
The Chinese also operate in the Taiwan Strait. According to the Australian defence minister, Richard Marles, there have been five cable-cutting incidents in the past 18 months in the narrow waterway between Taiwan and China. All the incidents have involved dragged anchors. This allows the Chinese and Russians a degree of plausible deniability.
For most of the 20th century, navies fought to keep open the sea lanes that carried oil, food and trade. Today they are increasingly defending something less visible but more important. Hidden beneath the oceans lies the nervous system of the global economy. Every bank transfer, military order, stock-market trade and video call depends on it.
The drone submarines of AUKUS are not being built to fight the third world war on the seabed. They are being built to stop someone else from starting it there.
Tom Arms is a journalist, author, broadcaster and lecturer in international affairs. He is the author of America: Made in Britain
