Tornado F3 jets from RAF Leuchars in Fife were sent to intercept two Russian aircraft spotted observing a Royal Navy exercise, it has emerged.
The jets were scrambled after the foreign planes were detected by radar in the skies over the Outer Hebrides.
They were identified as Russian Bear Foxtrot planes, commonly seen by RAF pilots during the Cold War.
The Russian aircraft were escorted from the area by the RAF who said no radio contact took place between the pilots.
A spokesman for the RAF refused to say when exactly the incident took place but revealed it had lasted no longer than 15 to 20 minutes.
An international live firing exercise, named Operation Neptune Warrior and involving 14 countries, was carried out in the area between 22 April and 3 May.
During the exercise 14 destroyers and frigates, submarines and patrol boats were engaged in collective training.