BRITAIN, America and Norway have launched a major hunt for a Russian submarine suspected of threatening a US aircraft carrier.

Specialist sub-hunting Poseidon planes have made 27 sorties to scour the Norwegian Sea since Sunday.

The RAF made eight P-8A Poseidon flights from RAF Lossiemouth in Scotland.

The Norwegian Air Force launched three from Evenes Air Base near Narvik, inside the Arctic Circle.

The US Navy used a base in Iceland but the scale of the operation meant they were reinforced by at least two US Poseidons from Sicily.

The Poseidon maritime patrol aircraft are armed with a range of Top Secret sensors, torpedos, missiles and sonar buoys which they can drop into the ocean to listen for the sound of submarines.

A defence source said the mission was a “highly unusual surge”.

It came as the USS Gerald R. Ford aircraft carrier strike group trained with the Norwegian Navy on drills in the North Sea.

The Ministry of Defence confirmed it was an operation not an exercise but refused to divulge details.

Ex-submarine captain Ryan Ramsay said: “This is Nato showing they are in control.”

He added: “Either they have already found the submarine, or submarines, and they are holding it.

“Or they haven’t got it yet and need to get hold of it.”

HMS Somerset, a specialist sub-hunting frigate, was also in Norwegian waters.

Tom Sharpe, a former Navy commander, said: “It looks like they have found a Russian submarine and they are hammering it.

“It is telling Russia: ‘We see you.’”

Most of the Poseidon aircraft turned off their transponders – which reveal their locations to other pilots – as they approached the search area.

But flight tracking websites showed an RAF Poseidon spent hours circling over the Norwegian Sea, some 60 miles west of the Lofoten Islands where the seabed drops a thousand metres.

The mission appears to have started around 7pm on Sunday and lasted almost 48 hours.

An MOD spokesperson said: “The UK’s P-8 Poseidon aircraft work continuously on operations, protecting national interests and keeping the UK and our allies safe.

“For security reasons we will not comment on operational details.”