Britain has scrambled RAF fighter jets for a second time this week after at least one Russian Bear bomber approached U.K. airspace.

The Ministry of Defense said Saturday that RAF Typhoons based at Lossiemouth in Scotland intercepted the aircraft on Friday. Images released with the statement showed one bomber, but the ministry declined to say how many aircraft were involved.

A similar incident took place Wednesday.

NATO earlier this week reported a spike in Russian military flights over the Black, Baltic and North seas and the Atlantic Ocean, with groups of Russian warplanes conducting large-scale maneuvers in international airspace.

Tensions have been high since Russia's annexation of the Crimean Peninsula from Ukraine in March. Alliance pilots have conducted 100 intercepts this year — three times more than in 2013.