RAF fighter jets were scrambled to intercept two Russian bomber planes approaching UK airspace in the North Sea.
The Ministry of Defence confirmed to the Standard that Typhoon aircraft from RAF Lossiemouth in Scotland took off on Monday morning.
The RAF jets escorted the Russian Blackjack bombers northwards and out of the UK's flight information region - the airspace over which Britain is responsible.
The closest the Russian jets came to UK land was 40 nautical miles, or around 46 miles. They came 30 nautical miles (34.5 miles) from British sovereign airspace.
A spokesman for the RAF said: "We can confirm that Quick Reaction Alert (QRA) Typhoon aircraft from RAF Lossiemouth scrambled to monitor two Blackjack bombers approaching the UK area of interest.
RAF vs the Russian Air Force
Today's incident is not uncommon
February 2016: Typhoons from the RAF dispatched to intercept Russian bombers heading towards UK.
September 2016: RAF planes intercept two Russian bombers west of Shetland.
October 2016: Jets from four European countries including Britain intercept Russian planes between Norway and Spain.
January 2017: Typhoons monitor Russian aircraft carrier as it moves through US waters.
May 2017: Two RAF planes leave Lossiemouth after Russian jets enter UK airspace.
September 2017: Two RAF fighter jets sent to head off Russian military planes approaching Scotland.
"The Russian aircraft were initially monitored by a variety of friendly nation fighters and subsequently intercepted by the RAF in the North Sea.
"At no point did the Russian aircraft enter sovereign UK airspace."
A Voyager refuelling aircraft from RAF Brize Norton also supporting the Typhoons during the operation.
The MoD said it could not confirm how many RAF aircraft had been sent because of operation security reasons.
Typhoons are combat aircraft used in air policing and high-intensity conflict.
They are often scrambled to police and intercept unidentified foreign planes illegally entering British airspace.
RAF Lossiemouth in north east Scotland is primarily used as a base for Quick Reaction Alert, where pilots are on duty 24 hours a day and ready at a moment's notice.
The incident on Monday follows a string of stand-offs in recent months between the RAF and Russian Air Force, although the Ministry of Defence said the RAF has routinely intercepted, identified and escorted Russian aircraft as part of its air defence role.
It added that Russian military flights have never entered UK sovereign airspace without authorisation.