The British military has uncovered evidence of covert Russian surveillance activity in UK waters, marking a significant escalation in Moscow’s underwater intelligence-gathering efforts.
Devices believed to be Russian-made sensors, designed to track the movements of Britain’s nuclear-armed submarines, have been found hidden around the British Isles in what senior defence officials describe as a sustained campaign of “greyzone” warfare.
The sensors—discovered both on the seabed and washed ashore—are understood to be part of a broader Russian initiative aimed at undermining Western critical infrastructure, including energy networks and undersea communication systems.
The Ministry of Defence (MoD) has not publicly disclosed the findings, citing national security concerns, but officials have confirmed the potential threat to the UK’s continuous at-sea nuclear deterrent.
Russia’s underwater operations, orchestrated largely by its Main Directorate for Deep-Sea Research (GUGI), form part of an intelligence strategy increasingly focused on the ocean floor.
Royal Navy sources report that unmanned underwater vehicles (UUVs) have been detected near critical subsea cables, while credible intelligence suggests some Russian oligarchs’ superyachts have been used to conduct reconnaissance missions in UK waters.
The Royal Fleet Auxiliary vessel Proteus, acquired by the MoD in 2023 and specially equipped for deep-sea surveillance, has emerged as the UK’s front line against these underwater threats.
The Sunday Times was granted access to the Proteus during a recent training exercise off the west coast of Scotland, where naval teams were deploying remotely operated vehicles through a hull opening known as a moon pool to simulate undersea threat detection and recovery.
According to naval sources, Russia’s capabilities in sea-bed warfare exceed those of many NATO members. Its fleet includes nuclear-powered mini-submarines and deep-diving manned and unmanned craft equipped to cut, tap, or destroy cables and other infrastructure.
In late 2023, the Russian spy vessel Yantar was observed near high-capacity transatlantic cables used by major technology firms. British surface and submarine assets, including HMS Astute, were deployed to shadow it.
Officials compare the current undersea competition to the Cold War space race. While the UK has begun to respond with investment in surveillance and autonomous maritime systems, analysts warn that Moscow’s head start leaves a significant capability gap.
Energy security is a key concern. A fifth of the UK’s electricity is supplied by offshore wind farms, whose power reaches the mainland via seabed cables. Additional undersea pipelines supply oil and gas, much of it from Norway. These systems are vulnerable to disruption from remotely-deployed explosives or mechanical sabotage.
The 2022 Nord Stream pipeline explosion, widely attributed to a state-backed actor, demonstrated the strategic implications of such vulnerabilities.
There are also growing fears regarding the UK’s dependence on undersea data cables—some of which carry sensitive banking information crucial to global financial markets. While redundancy has been built into the network, officials note that certain high-value cables would be difficult to replace quickly in the event of simultaneous attacks.
Efforts to protect this infrastructure date back over a decade. A 2017 policy paper by Rishi Sunak, then working with Policy Exchange, highlighted the national security risks associated with cable sabotage. Although the paper was not publicly released until years later, it prompted internal government reviews into how the UK might better safeguard subsea assets.
Recent developments suggest that Russia is expanding the scale and sophistication of its operations. In one instance, British officials confirmed that autonomous Russian vehicles were discovered adjacent to sensitive military cables without any accompanying support vessels nearby—indicating the drones had travelled long distances unaided, likely for reconnaissance or potential sabotage purposes.
In response, the MoD has prioritised the development of undersea surveillance capabilities. The Proteus, originally a Norwegian offshore support vessel, is now fitted with a range of UUVs, including the SeaCat, Gavia and Defender. These systems are capable of operating at significant depths and are equipped with advanced sonar, high-resolution imaging, and, in some cases, manipulator arms for explosive disposal.
As part of its strategic defence review, the government is considering the acquisition of a second surveillance vessel. A new initiative, Atlantic Bastion, has also been proposed, aimed at building a fleet of air, surface, and submersible platforms to patrol British and North Atlantic waters. Shorter-term objectives, under a project codenamed Cabot, may see private sector involvement in the funding and protection of undersea infrastructure.
Some former defence ministers have proposed a statutory funding mechanism, including a dedicated levy on technology and energy firms, to support national security efforts in this domain. “If this is a national endeavour, it is perhaps time to consider legislating for a level of assured protections,” said Anne-Marie Trevelyan, a former defence minister.
Meanwhile, the Royal Navy is reportedly reassessing its defensive doctrines. Although the UK has not maintained an active sea mine capability since the early 1990s, some officials have raised the possibility of reintroducing mines for deterrence purposes, particularly around high-value maritime assets and infrastructure.
As Defence Secretary John Healey continues negotiations with Norway on closer cooperation in undersea defence, the UK appears to be entering a new phase in maritime security policy. The geopolitical implications of sea-bed warfare are growing, and the next decade is likely to see increased military, industrial, and diplomatic focus on securing the ocean floor.
