Europe is right now fighting an enemy it cannot see and protecting a vulnerability it has not mapped. Undersea drones are taking the conflict between Russia and the West below water. But these sea drones are not looking for soldiers or civilian targets: they are patrolling infrastructure thousands of metres below sea level, aiming to prevent vital communications cables from being severed.
In a silent, deep-sea war, Europe and its allies are already counting the cost of Russian damage to its vital undersea cables
In a silent, deep-sea war, Europe and its allies are already counting the cost of Russian damage to its vital undersea cables – the spinal cords that connect us to the global economy. Responsible for the transfer of 99 per cent of all digital data and carrying $10 trillion (£7.5 trillion) of global transactions every day, damage to these cables – most only two to three cm in diameter – has already occurred in Norway, Finland and Taiwan. Russia was cited in an International Institute for Strategic Studies (IISS) report on sea sabotage, for cutting the C-Lion1 cable connecting Finland and Germany and the Arelion cable linking Sweden and Lithuania. If enough cables are simultaneously broken, ATMs can’t release cash and bank transfers don’t happen.
For Britain, this cable war is already here. After the Russian spy ship Yantar – a vessel previously tracked carrying cable-cutting technology – last month fired lasers at RAF pilots to blind them and stop them tracking their progress. Defence Secretary John Healey said, ‘My message to Russia and to Putin is this: we see you. We know what you’re doing.’
The Ministry of Defence has today responded with ‘Atlantic Bastion,’ which includes SG-1 Fathom – a sea drone with wings, enabling it to work aerially and below water – which can monitor marine saboteurs, spotting threats and linking with other military to send a response.
But Britain is playing catch up. In September, the parliamentary National Security Strategy Committee said it was ‘not confident’ the UK was equipped to protect its undersea cables, warning that an attack could cause ‘catastrophic disruption’ to vital financial and communications systems. It has hastily snapped up German company Helsing’s SG-1 Fathom marine drones.
Fatefully for Europe, many of these cables – happily laid during decades of peace time without a defensive thought in mind – are acutely vulnerable and in some places barely guarded at all. Ireland is a major weak spot for European defence, particularly the UK. Irish waters are the site of strategic cables that are critical for financial transactions between US to UK to EU, as well as energy pipelines. Yet, as the FT reported this month, Ireland – with the lowest defence spending in the EU of just 0.29 per cent – has just eight ships; no radar or sonar capability and no ability to receive live classified intelligence, meaning it relies heavily on UK and EU partners to receive threats. Unsurprisingly, Russian ships have been seen over these points since the Ukraine invasion.
On top of this, much of the cable damage is done not by warships, but by a 600-strong shadow fleet of cargo ships ‘owned’ by Russia through shell companies or listed in other territories such as Gabon, Benin or China. These ships can simply drag their anchor over a cable, snapping it or pulling it out.
In December 2024, the Estlink-2 undersea cable in the Gulf of Finland was believed to have been cut by the Cook Islands-flagged Eagle S, whose dragged anchor caused $60 million (£45 million) of damage. The Finnish authorities asked Eagle S – captained by a 39 year-old Georgian – to raise her anchor, but only the chain rose to the surface. Security forces took the ship into their possession, but the damage had already been done. (The crew have denied any wrongdoing.)
But tracking troublesome boats is difficult. Of the world’s 70,000 cargo ships, over 12 per cent do not have named, transparent owners. Tracking them is made harder by these boats regularly changing their names, says marine traffic expert Robin Lycka of Strise, a platform which helps major banks track and stop money laundering. In November 2024, the Russian-crewed oil tanker Odysseus changed her name to Varuna; by December, she was called Pushpa; and before 2024 was out she was already known as Kiwala.
The technology used to cut cables is also improving. China boldly unveiled in March a new marine vehicle capable of cutting lines at depths of up to 4,000 metres, twice the maximum operational range of existing subsea communication infrastructure. It has been designed to integrate with China’s advanced crewed and uncrewed submersibles like the Fendouzhe, Striver, and the Haidou series. This was the first time any country has officially disclosed that it has such an asset, capable of disrupting critical undersea networks.
Europe is now making moves. Sweden has signed a near £7 million plan with Saab to develop a sea drone capable of patrolling its waters, but smaller, independent firms are already in the water.
One of the weak spots with defensive drones is the amount of time they can stay in the water. German firm Euroatlas completed final trails with their autonomous Nato-backed sea drone Greyshark last month. This underwater drone can be in the water for 16 weeks at a time; travelling to a range of 11,000 miles and at a speed of ten knots. The Greyshark can work to fight submarines, or even detect and clear explosives and mines without risking human lives.
Euroatlas’s Verineia Codrean says the Greyshark’s main use will be intelligence, surveillance and reconnaissance. Reconnaissance could mean sitting in a hostile nations’ harbour and listening or following specific signals that are emitted by selected vessels or those on a designated path:
‘It can actually identify if this cargo ship is just dragging the anchor as part of stopping safely, or is it doing it, purposefully near a cable. Greyshark can also activate in a swarm. If one of them identifies a potential threat, they can communicate autonomously between themselves and go as a swarm at very high speed towards that specific ship that is dragging its anchor.’
Underwater drones are the best answer to the cable-cutting threat. As Europe’s fleet grows, they will be able to gather an incredible amount of data. And if one drone is taken out, it will have already transmitted its data, so a mission can be launched instantaneously.
With the threat to its undersea cables greater than ever, Europe is right to work fast in order to turn the tide against its adversaries. But is it too late?
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