Britain Says Russian Spy Ship Returned to U.K. Waters in Sign of Kremlin Threat

Britain on Wednesday warned that it faced a growing threat of aggression from Russia, asserting that a Russian spy ship had passed by the English coast for the second time in three months, in the latest incident that seemed designed to test British military capabilities.

John Healey, the British defense secretary, told Parliament that two Royal Navy ships were deployed for two days to monitor the passage of the Yantar, which he described as a Russian spy ship used for gathering intelligence and mapping Britain’s critical underwater infrastructure.

The incident is the latest in a series of incursions by Russian ships and aircraft around Britain and comes at amid rising concern in Europe about threats to critical infrastructure and possible sabotage, with Western intelligence services warning of the Kremlin’s intent to punish Europe for supporting Ukraine. Last year, when the Yantar was first detected in Britain’s waters, a British submarine nearby was monitoring it, the defense secretary disclosed on Wednesday.

While the authorities have linked Russia’s intelligence services to vandalism, arson and assaults across Europe in recent years, threats at sea have generated the most anxiety and prompted the boldest responses. Last week, NATO announced it was deploying warships, patrol aircraft and drones to protect critical infrastructure in the Baltic Sea after several undersea cables were cut, apparently by ships dragging their anchors along the sea floor.

Suspicion has fallen on vessels linked to Russia and China, with European Union vessels surrounding a Chinese-flagged ship for weeks and Finland seizing an oil tanker that experts and officials said might be part of Russian efforts to avoid Western sanctions.

Russian naval vessels have for years carried out missions near Britain and elsewhere. But Mr. Healey on Wednesday gave an unusual amount of detail about the normally shadowy world of military surveillance, underscoring the growing concern about Russian activity, in particular around vital underwater cables connecting Britain to continental Europe.

“Russia remains the most pressing and immediate threat to Britain,” Mr. Healey said on Wednesday, adding that he wanted to send a message to the Russian president, Vladimir V. Putin. “‘We see you. We know what you are doing. And we will not shy away from robust action to protect this country,’” he said.

Mr. Healey also told lawmakers that he had changed naval rules of engagement to allow the two British ships to get closer and monitor the movements of the Yantar, which has since left for Dutch waters.

Last November, the Yantar was observed loitering over critical British undersea infrastructure, Mr. Healey said, adding that on that occasion he had authorized a Royal Navy submarine to surface close to the Yantar to demonstrate that it had been monitored.

At the time, the British said, the Yantar was accompanied by a frigate, Admiral Golovko, and a supporting tanker, Vyazma, before the ships departed for the Mediterranean.

The Yantar, which has been in service for about a decade, is a highly sophisticated spy ship, developed by Russia’s Main Directorate for Deep-Sea Research specifically to hunt for critical underwater cables, said Justin Crump, the chief executive of a private intelligence firm, Sibylline, who has monitored the ship for years. The ship is equipped with two autonomous submersibles that can operate extensively and largely undetected, he said.

Though the Yantar could be capable of engaging in sabotage, Mr. Crump said, it was more likely that the ship would be used to find and possibly tap cables for intelligence gathering, and perhaps map their locations for future operations.

“They went to a lot of time effort and money to develop these ships, which have lots of impressive capabilities in this area,” he said. “And actually, for smashing up pipelines or cables, they’ve realized they could just drag an anchor on the seabed.”

Though intelligence services and experts say cutting underwater cables fit within what is understood to be the Kremlin’s covert playbook, it has proved difficult to actually uncover evidence linking Russia to recent episodes. The Kremlin has denied involvement in sabotage.

On Wednesday, the Finnish authorities announced that a preliminary investigation into the severing of several critical underwater cables last month was nearing conclusion, but said it would be premature to say if any one country was behind it. Investigators did conclude that the seized oil tanker, the Eagle S, which had departed a Russian port shortly before the cables were cut, had dragged its anchor for up to 100 kilometers across the sea floor, an action that experts said could hardly have been accidental.

Shipping experts have identified the Eagle S as belonging to Russia’s so-called shadow fleet, a group of aged tankers that Moscow uses to covertly transport crude oil around the world to fuel its war machine in Ukraine. The tanker and its crew remain in Finnish custody.

Russia has long shown an interest in the West’s network of undersea cables, experts said. Over the last several years, Russian naval and merchant vessels have spent time off the coast of Ireland, where bundles of undersea cables link Europe and North America.

“What we don’t know is why they are doing it,” said Elisabeth Braw, a senior fellow at the Atlantic Council who researches Russian maritime activity.

“Are they just signaling that we can sit on top of the undersea cables as much as we like and you can’t do anything about it?” she asked. “Are they conducting reconnaissance for future actions they might like to take and or are they conducting some sort of adversarial activities?

There is little that countries can do about it, Ms. Braw said, because international maritime law does not prevent Russian vessels from operating in these areas.

Alistair Carmichael, a British lawmaker who represents the islands of Orkney and Shetland, said “the activities of the Yantar may be an escalation.” But he added that he had warned for almost two years of Russian vessels operating around the Shetland Islands, north of mainland Scotland.

“This is a strategic threat to the United Kingdom as a whole but it is particularly acute for our island communities that rely on cables for digital and energy connectivity,” he said in Parliament.

Britain has been one of the most vocal supporters of Ukraine since Russia invaded it in 2022, and tensions between London and Moscow increased last year when Ukraine fired British Storm Shadow missiles into Russia’s Kursk region.

Amid rising tensions last October, Ken McCallum, the head of MI5, Britain’s domestic security service, said that Russian intelligence agents were on a mission “to generate mayhem on British and European streets.” He accused Russia’s military intelligence agency of “dangerous actions conducted with increasing recklessness,” including cases of “arson, sabotage and more.”

In April, British prosecutors charged five men with working on behalf of Russia to carry out an arson attack on a Ukrainian-linked business in Britain. And last fall, officials said that fires at shipping facilities in Britain and Germany had been caused by incendiary devices likely planted by Russian operatives.

Britain has recently reported more overt Russian military actions. Last September, it said that British Typhoon jets scrambled to intercept two Russian Bear-F aircraft operating near Britain’s airspace. It also said that the British Navy had shadowed four Russian vessels, including a Kilo-class submarine through the English Channel and the North Sea.

Johanna Lemola contributed reporting from Helsinki.