The British Royal Navy Deployed Warships and Aircraft After a Russian Submarine Entered Waters near the U.K.

Somewhere in the High North, several weeks ago, a Russian attack submarine entered international waters and started making itself known. It was persistent enough to demand attention and moving in a direction that put it close to British territorial waters. The Royal Navy found it and began tracking it around the clock.

That was exactly what Russia wanted.

While British and allied forces kept their eyes on the Akula-class submarine, a separate group of Russian vessels was already operating elsewhere, directly over the subsea cables that carry 99 percent of the world’s international internet traffic, banking data, and voice communications. The submarine was a decoy. The real operation was already underway.

On April 9, the UK Ministry of Defence made the entire episode public, saying British forces had identified both parts of the operation, exposed them, and forced all Russian units to retreat before they could complete their mission in secrecy. According to the official government statement, the operation lasted more than a month, involved approximately 500 British personnel, and included over 450 flying hours by RAF P8 Poseidon maritime patrol aircraft.

A Specialist Unit Built for Seabed Operations

The vessels conducting the underwater surveillance were not regular naval units. They belong to GUGI, Russia’s Main Directorate of Deep Sea Research, a dedicated military programme that develops and deploys specialist submarines and surface ships designed to operate on the seafloor. These assets are distinct from standard naval forces in both their equipment and their mission: they exist specifically to find, study, and, when ordered, interfere with the undersea systems that modern economies depend on.

In peacetime, GUGI vessels map cable routes, survey pipeline corridors, and gather data on the physical layout of underwater infrastructure across the North Atlantic. In a conflict, according to the UK government, that same knowledge and those same vessels would be turned toward sabotage. As detailed by Defence Matters, the British response involved a campaign of overt action designed to signal that the Russian units had been identified and were no longer operating covertly.

GUGI’s most recognised surface vessel is the Yantar, a ship that has appeared near sensitive cable routes on multiple occasions over the past several years. Last year it sailed close to UK waters, where it was tracked by a Royal Navy frigate and RAF P8 aircraft. During that operation, Russian personnel directed lasers at British pilots, an act the UK condemned.

Why the Cables Are the Target

The infrastructure GUGI was operating over is not a niche concern. Fibre optic cables carry the overwhelming majority of data crossing international borders, including banking transactions, government communications, corporate networks, and the everyday internet traffic of hundreds of millions of people. A deliberate strike on a small number of key cable junctions could sever connectivity between continents and disrupt financial markets.

The UK government specifically cited household energy bills in its public statement, drawing a direct line between critical undersea infrastructure and the cost of living for ordinary citizens. The argument is that disruption would ripple through energy trading systems, supply chains, and banking networks in ways that would eventually reach consumers.

Over 99 percent of international data traffic travels through these cables, according to the Ministry of Defence. Many of them pass through relatively shallow water in the North Sea and the English Channel, making them more accessible to interference than deeper Atlantic routes. That geography puts British waters at the centre of a strategic vulnerability that extends well beyond the UK’s own national interests.

Timed to Exploit Divided Attention

The timing of the operation was deliberate. Russia launched it while international military attention was concentrated on the Middle East, with the clear expectation that NATO surveillance in the High North would be under strain. Defence Secretary John Healey addressed the overlap directly.

“While the eyes of many, understandably, were on the Middle East, our British Armed Forces were simultaneously responding to rising Russian threats north of the UK.”

Working alongside Norway and other allies, Britain tracked both the Akula and the GUGI vessels at the same time. RAF P8 aircraft dropped sonobuoys across a wide area to monitor submarine movements below the surface. Royal Navy ships covered thousands of miles during the response. Once Russian forces understood they had been identified, the UK shifted from covert tracking to overt surveillance, making the monitoring deliberately visible. Both the Akula and the GUGI units turned back toward Russia.

Ten Days of Surface Tracking in the Channel

While the submarine operation was unfolding in the High North, a separate Russian naval group was transiting the English Channel and North Sea. The Royal Navy tracked five vessels over ten days: the destroyer Severomorsk, the frigate Admiral Grigorovich, the landing ship Aleksandr Shabalin, the tanker Kama, and the Kilo-class submarine Krasnodar.

As reported by Zona Militar, the British ships deployed for the monitoring were HMS Somerset, HMS St. Albans, HMS Mersey, and the support tanker RFA Tideforce, with Wildcat and Merlin helicopters providing aerial coverage throughout. HMS Somerset’s role was conducted under Operation Ceto, the Royal Navy’s standing mission to monitor submarine activity in and around British waters.

France, the Netherlands, and Belgium also contributed ships and aircraft to the monitoring effort. Lieutenant George Hage of HMS Mersey noted that maintaining continuous presence to watch Russian movements “is not easy, especially with the increase in activity in recent months.”

Investment in Seabed Defense

The UK has recorded a 30 percent increase in Russian naval activity near its waters over the past two years. In direct response, the government announced an additional £100 million for its fleet of P8 Poseidon submarine-hunting aircraft. The Atlantic Bastion programme, designed to combine autonomous underwater systems with advanced sensors integrated across Royal Navy warships, is also receiving investment following the Strategic Defence Review.

Prime Minister Keir Starmer framed the public disclosure as a deliberate choice. “I am determined to protect the British people from paying the price for Putin’s aggression in their household bills,” he said. “That is why we will not shy away from taking action and exposing Russia’s destabilising activity that seeks to test our resolve.”

The Royal Navy confirmed its ships and aircraft remain on standby should Russian forces attempt to return to the area.