British Typhoon jets have been scrambled to intercept two Russian Blackjack bombers that flew close to British airspace.
The RAF aircraft were sent up from RAF Lossiemouth in Scotland when the bombers passed to the west of Shetland, but at no point did the planes stray into UK airspace.
Aircraft from RAF Coningsby in Lincolnshire were also launched as a "precautionary measure" on Thursday but were not required to intercept the Russian jets.
A Royal Air Force spokeswoman said: "We can confirm that quick reaction alert Typhoon aircraft from RAF Lossiemouth intercepted two Russian Blackjack bombers and escorted them while they were in the UK area of interest."
In December last year British military officials held talks with their counterparts in Moscow over "incursions" of Russian aircraft around the UK.
Defence Secretary Sir Michael Fallon said the talks were aimed at finding ways of heading off any "miscalculation or accident".
The encounter comes amid heightened tension between Moscow and Washington during a week in which Russia accused the US-led coalition of stoking Syria's civil war.
A fragile US-Russia brokered ceasefire in the country was tested at the weekend when a US-led airstrike in which Britain played a part killed 60 Syrian soldiers near Deir ez-Zor.
While the US said the strike was an accident, Russia claims it was carried out deliberately by the US.
Hours later a UN humanitarian convoy near Aleppo was attacked killing 20 aid workers. Russia denied responsibility despite suggestions from Washington that Russian Su-24 jets were to blame.