Russia ran a secret submarine operation in British waters that threatened vital energy and data cables, John Healey has revealed.
The Defence Secretary said the UK had monitored a Kremlin attack submarine and two spy vessels in the North Sea for a month before they retreated.
He added that the British warships dropped sonar buoys to deter the submarines from targeting subsea cables, which provide essential telecommunications and carry large volumes of data between countries.
The admission raises further questions about the state of Britain’s Armed Forces a day after The Telegraph observed a Russian warship escorting two sanctioned tankers through the English Channel.
The Admiral Grigorovich, a Black Sea fleet frigate, accompanied the pair in open defiance of Sir Keir Starmer’s threat to seize Moscow’s shadow fleet vessels. Putin’s flotilla was observed cruising past the south coast as a British naval vessel followed behind.
At Downing Street on Thursday, Mr Healey revealed that Britain had monitored a Russian Akula-class nuclear-powered attack submarine and two specialist submarines belonging to a deep-sea research programme known as Gugi, run by Moscow’s defence ministry.
The Defence Secretary said the attack submarine was a decoy, while the two Gugi vessels spent time over critical undersea infrastructure.
The Royal Navy regularly dropped sonar buoys next to the Russian submarines to let them know that they were being watched.
Mr Healey said he was “confident” that no cables or pipelines had been damaged, but added that this would have to be verified by North Sea allies.
He added: “To President Putin, I say: we see you we see your activity over our cables and our pipelines, and you should know that any attempt to damage them will not be tolerated and will have serious consequences.”
Sir Keir Starmer has faced repeated criticism about the state of the Royal Navy and the Armed Forces.
After an Iranian-made drone hit RAF Akrotiri, on Cyprus, HMS Dragon – Britain’s only deployable destroyer – was sent to the Middle East, but took three weeks to arrive and has already had to return to port because of water supply problems.
Lord West, a former First Sea Lord and a Labour peer, said the military was in a “parlous state”, while Gwyn Jenkins, the First Sea Lord, warned that the Navy “had work to do” before it was capable of fighting a war successfully.
Donald Trump, the US president, has described the Navy’s two aircraft carriers as “toys”, and Pete Hegseth, his defence secretary, has mocked Britain’s “big, bad Royal Navy”.
During his press conference on Thursday, Mr Healey rejected the president’s criticism but admitted the Government could be doing more to stop sanctioned tankers in the Channel.
Last month, Sir Keir gave special forces the authority to capture Russian shadow fleet vessels, saying he would hit the shadow fleet “even harder” if they sailed through British waters. However, Britain has yet to seize a single Russian vessel.
On Wednesday, The Telegraph observed the Admiral Grigorovich escort a pair of Russian shadow fleet ships in the Channel while the RFA Tideforce, a Royal Fleet Auxiliary tanker, trailed in their wake.
On Thursday, the Ministry of Defence said the Royal Navy had completed 10 days of operations monitoring Russian warships and a submarine in British waters.
Naval helicopters and ships shadowed four Russian navy vessels, including a surfaced submarine, in the Channel and the North Sea.
Portsmouth-based HMS Mersey worked with a Wildcat helicopter to report on the movements of Admiral Grigorovich, Aleksandr Shabalin, a Ropucha-class landing ship, and Krasnodar, a Kilo-class submarine. Separately, HMS Somerset, a Type 23 frigate, intercepted Severomorsk, a Russian Udaloy-class destroyer, and Kama, an accompanying oiler, near the coast of Brittany, France.
The Somerset will now begin four months of operations in the North Atlantic to monitor submarine movements and protect undersea infrastructure.