A fleet of Royal Navy ships were scrambled to shadow Russian warships that sailed into UK waters.
Seven Russian vessels were spotted in the English Channel and North Sea and were followed by nine British ships.
Type 23 frigates HMS Kent, HMS Sutherland, HMS Argyll and HMS Richmond joined Offshore Patrol Vessels HMS Tyne and HMS Mersey along with RFA Tideforce, RFA Tidespring and HMS Echo for the large-scale operation.
The shadowing activity went on for more than a week but is now completed.
It was supported by NATO allies, the Royal Navy said in a statement.
Lieutenant Nick Ward, HMS Tyne’s Executive Officer, said: “As the Armed Forces are helping the NHS save lives in the UK, it’s essential the Navy continues to deliver the tasks we have always performed to help keep Britain safe.
“This is very much part of routine business for HMS Tyne and represents one of the many roles our patrol vessels perform in support of the Royal Navy’s commitment.
“This is our core business and represents an enduring commitment to uphold the security of the UK.”
Royal Navy sailors and aircrew 'were monitoring every movement of the Russian ships using state-of-the-art radar, surveillance cameras and sensors', the organisation said.
They were supported by Merlin and Wildcat helicopters of 814 and 815 Naval Air Squadrons.
A statement released by the Royal Navy continued: "Portsmouth-based HMS Tyne spent more than a week working in the English Channel, in often challenging seas, keeping a close eye on the Russian vessels as they pass the south coast.
"Three Steregushchiy-class corvettes, two Ropucha-class landing ships and two Admiral Grigorovich-class frigates were observed during the operations, plus their supporting auxiliary ships and tugs."
A Navy Merlin helicopter swooped over the vessels on a spying mission, it emerged
HMS Sutherland’s Operations Officer, Lieutenant Hannah Lee, said: “Our successful integration into the maritime group proves our ability to adapt to task group operations at short notice.
“Having proved we can work together and contributed once again to NATO operations, we now look to return to UK national tasks in support of the very highest defence priorities.”
NATO duties also saw HMS Sutherland support the French carrier strike group led by aircraft carrier Charles de Gaulle in recent weeks.
HMS Sutherland, working alongside French, Norwegian, German and Danish ships, then carried out surface and air defence exercises as well as carrying out joint gunnery training.
The shadowing of Russian ships is not unheard of.
The HMS Tyne sailed out to keep an eye on the Smolnyy Perekov on Christmas Eve when it came close to entering UK territorial waters.
The ship remained at sea on Christmas Day to monitor the Russian vessel, the Royal Navy said in a statement.
