Underwater espionage: Russia monitored British nuclear subs near UK waters

According to the newspaper, the discovery was considered a potential threat to national security, but the government never made the information public. The report also claims that Russian unmanned vehicles were detected near undersea communication cables.

The sensors were allegedly placed to gather intelligence on Britain’s four Vanguard-class nuclear-powered submarines, each armed with nuclear warheads. At least one of these vessels is continuously at sea as part of the UK's policy of continuous at-sea deterrence, The Sunday Times noted.

Last year, the Russian spy ship Yantar was spotted off the UK coast. The vessel is equipped for deep-sea missions, including mapping and potentially damaging subsea infrastructure.

According to the report, the Ministry of Defence received intelligence suggesting that Russian oligarch-owned superyachts were conducting underwater reconnaissance in British waters even before Russia’s 2022 invasion of Ukraine.

"Several of these vessels are equipped with so-called moon pools, which can be secretly used to deploy deep-sea reconnaissance equipment and divers," the paper wrote. One British warship, HMS Albion, was reportedly monitored by a Russian superyacht in Limassol, Cyprus, back in 2018.

Senior military officials have compared the technological race for undersea dominance to the Cold War-era space race between the United States and the Soviet Union.

The revelations underline how the UK is now operating in a “grey zone of warfare” with Russia, former defence minister Tobias Ellwood told The Guardian. He warned that the UK is highly exposed to maritime threats, noting that “90 percent of British data comes through the sea, and 60 percent of our gas arrives via a single pipeline from Norway.”

Ellwood called for an expansion of the modern Proteus-class vessels tasked with monitoring and protecting underwater infrastructure.

Privately, some Navy personnel believe the UK should even consider reintroducing its capability to deploy naval mines — a practice abandoned since the end of the Cold War — to boost maritime security.

“There should be no doubt: a war is raging in the Atlantic. It’s a cat-and-mouse game that’s been playing out since the Cold War ended — and now it’s heating up again,” one military source told The Sunday Times.

The report also noted that the UK government is considering new regulations requiring technology and energy firms to work more closely with the military and help fund the protection of undersea infrastructure.