British fast jets scrambled from two bases to intercept and escort Russian long-range, nuclear-capable bomber aircraft "approaching the UK area of interest", the Royal Air Force said.
It is relatively rare for the RAF to have to launch from both Quick Reaction Alert bases - one in Scotland, the other in Lincolnshire.
The first Typhoon warplanes took off from RAF Lossiemouth at about 10:45am on Friday and escorted the two Russian Tu160 Blackjack bombers, which were flying over the North Sea.
Another scramble then took place from RAF Coningsby at about 12:15pm to take-over the escort operation and watch the Russian planes until they were out of the UK's area of interest.
The Russian bombers never entered UK sovereign airspace.
RAF jets scramble about 10 times a year from the UK in response to Russian aircraft but the interception on Friday came at a time of heightened tensions between Moscow and western allies.
The UK and other NATO partners are understood to be concerned about a build-up of Russian troops on Russia's border with Ukraine, amid fears that the Kremlin might be preparing for a possible invasion. Moscow has denied such claims as inflammatory.
With the British interception, a Royal Air Force spokesperson said the Typhoon jets were supported by a Voyager air-to-air refuelling aircraft, which took off from RAF Brize Norton in Oxfordshire at about 10am.
The whole mission was completed by around 2:30pm.
"Quick Reaction Alert Typhoon fighters based at RAF Lossiemouth and Coningsby were scrambled today against unidentified aircraft approaching the UK area of interest," the spokesperson said.
"Subsequently we intercepted and escorted two Russian Tu160 Blackjack, long range strategic bomber aircraft."
The RAF declined to say how many of their fast jets took part in the response.
The Russian planes had not been communicating with air traffic agencies, triggering the scramble.
The Russian defence ministry on Thursday claimed it had scrambled a fighter jet to intercept a British spy plane operating near Crimea.
A UK Ministry of Defence spokesperson said: "We do not recognise these claims. Wherever the RAF operates, it does so in full compliance with international laws and exercises its right to freedom of overflight."