Russian underwater surveillance sensors, believed to be part of an effort to spy on the U.K.’s nuclear submarines, have been discovered concealed in the waters surrounding Britain, a report by the Sunday Times has revealed.
The Royal Navy discovered several of these sensors after they washed ashore. The discovery of these covert devices sparked fears that Moscow is secretly monitoring the UK nuclear submarine fleet and potentially plotting sabotage against major parts of the UK’s undersea infrastructure.
The UK has four Vanguard-class submarines, which carry Britain’s nuclear missiles.
“There should be no doubt, there is a war raging in the Atlantic. This is a game of cat and mouse that has continued since the ending of the Cold War, and is now heating up again. We are seeing phenomenal amounts of Russian activity,” a senior British military official told the Sunday Times.
However, despite military officials flagging the discovery as a major national security threat, the country’s Defense Ministry (MoD) has kept details about the discovery secret. The Sunday Times report also did not disclose the information about the sensors’ location.
Kermlin’s Undeclared War
UK Defense officials suspect the operation to be a part of Russian President Vladimir Putin’s broader “greyzone” strategy, an undeclared form of warfare targeting undersea cables, pipelines, and other critical systems.
In the last 15 months, as many as 11 deep-sea communication cables in the Baltic Sea have been damaged, with Russia and China as prime suspects.
In December last year, the Estlink 2 power cable between Finland and Estonia was damaged, along with four telecommunications cables (FEC-1, FEC-2, CITIC Telecom, and another unnamed line). Finnish authorities suspect the Cook Islands-flagged Eagle S, part of Russia’s “shadow fleet,” caused the damage by dragging its anchor.
This is being investigated as potential sabotage, with a 60-mile anchor drag mark found on the seabed.
In January 2025, a fiber-optic cable connecting Latvia and Sweden (Ventspils to Gotland) was damaged, prompting a Swedish sabotage investigation.
Also, Russia’s underwater surveillance efforts extend beyond sensors. The Sunday Times investigation reveals that unmanned Russian vehicles have been found near deep-sea communications cables, and credible intelligence suggests that Russian oligarchs’ superyachts may have been used for underwater reconnaissance.
Crucially, these seabed communication cables connect the UK to the rest of the world. A senior source said there are 60 internet cables currently connecting Britain to the rest of the world, some of which are not public.
“Our role is to both defeat any threats to the UK as well as take it out of the greyzone. We do the latter by understanding who is involved and providing that evidence to avoid misunderstandings and make those who threaten the UK accountable for their actions,” said Captain Simon Pressdee.
Russia’s Deep-Sea Research Vessel Yantar
The Sunday Times investigation further suggests that Russia’s military program, particularly its deep-sea research vessel Yantar, poses a significant threat to Britain’s critical underwater infrastructure.
The Yantar is Russia’s most advanced intelligence-gathering vessel, designed as an upgrade to older spy ships.
It can hover over a location and deposit and retrieve objects from the seabed. It also hosts manned deep-sea submarines that can reach 6,000 meters below the water and deep-sea robots tethered to the ship.
The ship has been repeatedly spotted near vital internet cables and data centers. It was spotted in the UK waters in January this year.
According to Royal Navy sources, the Yantar’s presence in UK waters signals Russia’s escalating efforts to infiltrate vital communication lines and military cables.
UK Countermeasures
Amid increasing Russian spy activities in UK waters, the government is ramping up efforts to safeguard the country’s vital undersea infrastructure and seeking support from private tech firms to upgrade its undersea defenses.
A new project codenamed Cabot will be launched to safeguard vital undersea infrastructure. The seven-year, £400 million (US$513.8 million) program aims to deliver two uncrewed system technology demonstrators: the PROTEUS rotary-wing uncrewed air system; and the CETUS extra-large uncrewed underwater vehicle (XLUUV) for anti-submarine warfare (ASW) and search capability in the North Atlantic.
The UK has also operationalized RFA Proteus, a deep-sea surveillance vessel tasked with countering Russian threats in domestic waters. It is the only surface ship in the UK’s arsenal capable of patrolling the deep-sea areas where Russia’s most advanced threats, such as nuclear-powered mini-submarines, could be lurking.
However, despite these developments, UK defense officials believe that more aggressive steps should be implemented, including laying sea mines around sensitive areas, a strategy not used since the Cold War.
A Ministry of Defense spokesperson said, “We are committed to enhancing the security of critical offshore infrastructure.”
“Alongside our NATO and Joint Expeditionary Force allies, we are strengthening our response to ensure that Russian ships and aircraft cannot operate in secrecy near the UK or near NATO territory, harnessing new technologies like AI and coordinating patrols with our allies. And our continuous-at-sea nuclear deterrent continues to patrol the world’s oceans undetected as it has done for 56 years.”
- Sumit Ahlawat has over a decade of experience in news media. He has worked with Press Trust of India, Times Now, Zee News, Economic Times, and Microsoft News. He holds a Master’s Degree in International Media and Modern History from The University of Sheffield, UK.
- He can be reached at ahlawat.sumit85 (at) gmail.com
