A number of Russian submarines are reportedly being hunted off the UK coast.
Three NATO search planes, Royal Navy anti-submarine frigate HMS Sutherland and a Trafalgar class hunter-killer submarine have been scouring seas off west Scotland in the search, according to the Sun newspaper. It quotes a Whitehall source as saying:
"There are believed to be multiple Russian submarines off the coast of Scotland. Various assets have been deployed to identify their location and understand their intentions."
It's believed the submarines are nuclear-powered Akula-class boats.
Russia's believed to have nine currently in service, each with a crew of around 70.
It comes after three Russian submarines reportedly joined the country's naval battle group heading towards Syria last month.
The Royal Navy and NATO were said to have been tracking two Akula-class subs and a diesel-powered Kilo-class boat.
They were believed to have been making their way towards the Russian fleet headed by the aircraft carrier Admiral Kuznetsov, which travelled through the English Channel last month.
It was reported last May, meanwhile, that Canadian submarine HMCS Windsor had been sent on a similar underwater hunt after Russia deployed five attack subs to the North Atlantic. A Royal Navy spokesman said:
"It’s our long-standing policy that we don’t comment on submarine operations. As part of our £178bn equipment plan the UK has a range of assets to patrol our seas."