The Royal Navy has been monitoring a Russian spy ship task group passing the UK.
HMS Mersey and a Wildcat helicopter from RNAS Yeovilton were dispatched to follow the progress of three Russian warships as they made their way through the Channel.
The Russian spy ship Feodor Golovin, landing ship Alexander Ostrakovskiy and tanker Yelnya have been supporting Russian operations in Syria and are believed to be returning to their base ports in the Baltic and Barents seas.
HMS Mersey broke off from a regular fishery protection patrol in home waters in order to meet the Russian vessels as they approached the Channel, taking over from the French Navy.
The patrol ship spent 72 hours tracking the Russians as the vessels made their way into the North Sea, handing over to the Dutch Navy once the three ships had passed through the Strait of Dover.
Lieutenant Alexandra Karavla, the patrol ship's Executive Officer, said:
"Ships like HMS Mersey are the eyes and ears of the Royal Navy around the UK – we are at sea for 320 days a year, so Mersey provides the Navy with a ship ready to respond at short notice like this."
"Although her routine business is patrolling UK waters and helping to enforce fishery legislation, HMS Mersey was tasked to locate, meet and escort the ships through the English Channel.
"In this, we have been well supported by a Royal Navy Wildcat from 815 Naval Air Squadron and by NATO colleagues. Operations like this would not be possible without such support and co-operation.
"This tasking proves why HMS Mersey is vital to UK defence. The flexibility and options these offshore patrol vessels provide to the government is evident in the variety of tasking undertaken."
At the end of 2017, HMS St Albans escorted the new Russian warship Admiral Gorshkov through the North Sea.
More recently, HMS Westminster was activated to keep track on the activities of two Russian frigates and their support vessels returning to the Baltic after operations in the Middle East.