The nuclear-powered hunter-killer submarine surfaced close to the Yantar to let the Russian ship know it was being watched.

A Royal Navy submarine was authorized to surface close to a Russian ship "strictly as a deterrent measure," British Defense Secretary John Healey said.

A Russian spy ship has been monitored by the Royal Navy after it entered UK waters earlier this week, the defence secretary has said - as he issued a warning to President Vladimir Putin.

U.K. Defense Secretary John Healey on Wednesday issued a warning to Russian President Vladimir Putin after reporting a Russian spy ship had entered British waters earlier this week.

A Royal Navy nuclear-powered submarine was deployed to warn off a Russian spy ship operating in the English Channel, the government has revealed. The hunter-killer submarine surfaced close to the Russian vessel The Yantar which was loitering over critical undersea cables.

Defence secretary John Healey said the Russian vessel Yantar is being 'used for gathering intelligence and mapping the UK’s critical underwater infrastructure'

The Royal Navy has been monitoring a Russian spy ship after it was spotted around UK waters earlier this week, the defence secretary has told MPs. John Healey said the vessel, Yantar, was used for gathering intelligence and mapping the UK's critical underwater infrastructure.

The Royal Navy of the United Kingdom has been closely tracking a Russian spy ship recently spotted in British waters, sparking concerns about Russia’s activities near the U.K.’s critical underwater infrastructure.

A Royal Navy submarine was authorized to surface close to a Russian ship "strictly as a deterrent measure," British Defense Secretary John Healey said.

Defence Secretary John Healey said Russia "remains the most pressing and immediate threat to Britain", and added that "any threat will be met with strength and resolve".

The Defence Secretary told the Russian leader: "We see you, we know what you are doing and we will not shy away from robust action to protect this country." It came as the minister told MPs the Russian vessel, Yanta, was currently in the North Sea having passed through British waters.