RAF Typhoons have been scrambled to intercept two Russian bombers heading towards UK airspace, the Ministry of Defence has said.
The jets were dispatched from RAF Coningsby in Lincolnshire on Wednesday afternoon following the security alert.
A spokesman said two Russian Blackjacks were escorted in an "area of interest" but did not enter UK airspace.
Russian military planes have been intercepted near the UK at least six times in the past 12 months.
In November a similar incident saw two Russian bombers escorted by Typhoon jets after being detected flying over the Atlantic.
The RAF said such incidents were not uncommon and fighter jets were dispatched on a "quick reaction alert".
Andrew Brookes, a fellow at the Royal United Services Institute and former RAF pilot, said there was no reason why the planes should enter UK airspace and the incidents were signs of "Russia flexing its muscles".
"They are not trying to provoke a war," he said. "It isn't a Cold War... they are just using these tactics to poke us in the chest."
In December, British military officials held talks with their counterparts in Moscow over "incursions" of Russian aircraft around the UK.
Russia has not crossed into UK airspace but has flown close to the boundary.
RAF Typhoon specifications
Max speed: 1.8 Mach
Maximum altitude: 55,000ft
Weapon options: Paveway IV, AMRAAM, ASRAAM, Mauser 27mm Cannon, Enhanced Paveway II