Putin’s shadow fleet could cripple Britain from beneath the North Sea

Writing exclusively for LBC Opinion, Patrick Cronin, a defence and security expert at PA Consulting, said the UK does not yet have the continuous monitoring capability needed to detect suspicious activity around vital undersea cables, pipelines and power links before damage is done.

He warned that the North Sea seabed, which carries fibre-optic cables, gas pipelines and energy interconnectors, presents a major target to the Baltics, for hostile actors seeking to disrupt Britain below the threshold of open conflict.

It follows a series of incidents in the Baltic Sea, where undersea infrastructure has been damaged in circumstances that remain disputed but have raised serious concern across Nato.

In November 2024, two submarine cables were severed in the Baltic within hours of each other. A month later, the Estlink 2 power cable between Finland and Estonia was taken out of service for seven months, with repairs costing around €60 million.

In each case, vessels linked to Russia’s shadow fleet were reported to have been in the area.

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Mr Cronin said the suspected method used in the Baltic was “deliberately unsophisticated”, with ships potentially dragging anchors across known cable routes for tens or even hundreds of kilometres.

He warned the approach required no specialist equipment, left ambiguous evidence and made legal attribution difficult, making it a cheap but effective form of sabotage. Humanity, apparently not content with inventing cyber warfare, has now rediscovered the destructive potential of dragging heavy metal along the seabed.

“The North Sea seabed, carrying the fibre-optic cables, gas pipelines, and interconnectors that underpin our energy security, presents a similar, and arguably more consequential, target,” he said.

He added that shadow fleets, made up of hundreds of tankers operating under opaque ownership structures and often with tracking systems disabled, routinely transit both the Baltic and North Seas.

“What they do along the way is not fully understood,” he said. “And the UK’s capacity to monitor that traffic continuously, detect anomalous behaviour in real time, and act before damage occurs is not yet where it needs to be.”

Earlier this year, LBC reported that MPs had been warned Britain was falling behind Russia in the undersea domain, leaving vital data cables and energy infrastructure exposed to disruption and sabotage.

In evidence to the House of Commons Defence Committee, experts said Russia was already using submarines and deep-sea platforms as part of a sustained campaign of hybrid warfare, targeting critical infrastructure in ways that are difficult to detect, attribute or deter.

Professor Peter Roberts told MPs that Britain was effectively “on the front line” underwater, warning that the UK hosts 119 data cables and acts as a gateway between Europe, the Mediterranean and the United States.

He said around $17 trillion worth of trade a day passes through UK data cables, while Britain’s energy pipelines also make it highly exposed.

“The energy pipelines are enormous connectors through the UK. So the UK is on the front line,” Prof Roberts said.

He added that while undersea cables are armoured as they approach the shore, “for most of their length across the seabed they have no protection at all”.

The committee heard there are around 42,000 kilometres of undersea cables in UK waters alone, with hundreds of breaks recorded each year. Most are caused by accidental damage, such as fishing activity or natural movement, but experts warned the UK still lacks a clear picture of what is happening around the cables on the seabed.

Mr Cronin said the answer was not simply to deploy more naval vessels, although he said that would help.

Instead, he called for an overlapping surveillance network using underwater acoustic sensors, autonomous vehicles, satellite monitoring and AI-enabled vessel tracking to build a clearer picture of activity around critical infrastructure.

He said several of the capabilities already exist in early form, including among smaller British and allied companies, but warned the path from promising prototype to Ministry of Defence procurement can be slow and uncertain.

“These companies need clearer demand signals, longer planning horizons, and a willingness from defence to trial emerging technology at pace rather than wait for a fully matured solution,” he said.

“Without that, many will struggle to survive long enough to deliver what the UK increasingly cannot do without.”

Mr Cronin said the Royal Navy’s NavyX unit, which trials emerging technologies to get new capabilities to the fleet faster, offered a model for how Britain could speed up undersea innovation.

He also pointed to Nato’s Baltic Sentry operation, launched in January to improve seabed security in the Baltic, as a model that could be applied to the North Sea.

The operation is designed to improve coordination between Baltic states, establish clearer protocols and make it harder and more costly for shadow fleet vessels to operate.

Mr Cronin said Britain was well placed to drive a similar effort for the North Sea through Nato and the Joint Expeditionary Force, given its geography and regional relationships.

“We already have, or are close to having, the technology to build a far clearer picture around North Sea infrastructure,” he said.

“The missing ingredient is not innovation, but the commissioning framework that gives innovation somewhere to go.”

He warned that getting this right was no longer a long-term ambition, but essential to protecting the North Sea systems that underpin Britain’s energy security.