Three Russian submarines conducted a covert operation over cables and pipelines in waters north of the UK, Defence Secretary John Healey said. A British warship and aircraft were deployed to deter the malign activity by Moscow and there was no evidence of any damage to UK infrastructure in the Atlantic, he added.

Addressing Russian President Vladimir Putin directly, Healey said: 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.

The Russian embassy in London has denied Healey's claims, according to Moscow's state news agency Tass.

The UK is dependent on its undersea cables and pipelines for its data and energy. There are around 60 undersea cables that come ashore at several points along the UK coastline, particularly around East Anglia and South West England. More than 90% of the UK's day-to-day internet traffic travels via these undersea cables.

Healey told a Downing Street press conference on Thursday that Russia had sent an Akula class submarine as a diversionary tactic while two of its GUGI spy submarines carried out the surveillance of these cables.

Healey said the attack submarine soon left UK waters and went back to Russia after it was monitored, while the two GUGI vessels remained. Tass reported that the embassy said Russia was not threatening underwater infrastructure, which is truly critical to the UK. We are not using aggressive rhetoric in this regard.

The Royal Navy deployed frigate HMS St Albans, fuel tanker RFA Tidespring, and anti-submarine Merlin helicopters to track all three of the Russian submarines. Other nations were involved in tracking the Russian activity - though Healey mentioned only Norway by name.

Our armed forces left [Russia] in no doubt that they were being monitored, that their movements were not covert, as President Putin planned, and that their attempted secret operation had been exposed, Healey said.

We watched them, we were able to track them, we dropped sonar buoys to demonstrate to them that we were monitoring every hour of their operation.

The GUGI units, while not widely known, are integral to Russian naval operations, specializing in underwater surveillance and reconnaissance. These submarines can potentially disrupt undersea infrastructures crucial for the UK's data and energy supplies, representing a significant security concern amid ongoing tensions over Russia's military actions in Ukraine.