The sighting of a periscope off the west coast of Scotland in November sparked a NATO effort to track down the submarine.
A CP-140 Aurora aircraft along with planes from the U.S. and France took part in the search organized by the Royal Air Force.
The search continued until last week, the BBC has reported.
Britain no longer has its own fixed-wing aircraft specifically designed to search for submarines so it called in aircraft from its allies, noted BBC defence correspondent Jonathan Beale in his report.
The UK would not confirm it was looking for a foreign submarine Beale noted in his report but there have been reports of increased Russian military activity in the area.
The UK’s Ministry of Defence stated that it “requested assistance from allies’ forces for basing maritime patrol aircraft at RAF Lossiemouth for a limited period”.
At the height of the search, two U.S., the RCAF Aurora, and a French Dassault Atlantique were involved, Beale wrote. An RAF Sentinel spy-plane and a Royal Navy warship also took part, he added in his report.
Jonathan Beale’s full article can be found here: