Fighter jets have been scrambled from a Scottish base for the second time in five days to monitor Russian military aircraft flying close to UK airspace.
The Ministry of Defence (MoD) said Typhoons from RAF Lossiemouth in Moray responded to the incident off Scotland's north east coast.
On Friday, Typhoons from Lossiemouth responded to Russian aircraft in a similar situation.
A Voyager tanker supported the Typhoons in the latest incident.
The tanker from RAF Brize Norton in Oxfordshire was made available for refuelling the jets during the operation.
Russian Tupolev Tu-160 long range bombers were involved in both Friday and Wednesday's incidents.
While it was the second incident in days involving RAF Lossiemouth, it was the third in a week for the UK. Crews from RAF RAF Coningsby in Lincolnshire responded to an incident last Wednesday.
Russian jets did not enter UK airspace in any of the incidents.
Lossiemouth and Coningsby are the RAF's quick reaction alert stations tasked with protecting UK airspace.
An RAF spokesman said: "We can confirm that RAF quick reaction alert Typhoon aircraft from RAF Lossiemouth scrambled to monitor two Blackjack bombers while they were in the UK area of interest.
"At no point did the Russian aircraft enter UK territorial airspace."
Similar incidents have occurred in the past.
The latest two come as Nato and Australian forces are in Scotland for Exercise Joint Warrior.
Warships, aircraft and more than 10,000 personnel are involved in the UK-led military training, which largely takes place in the sea and air around the Highlands and Islands.