Fighter jets stationed at Leuchars in Fife were scrambled to monitor two Russian long-range supersonic bombers just days after a similar incident.
The RAF Typhoons joined Norwegian and German aircraft in flying towards the Tu-160 Blackjacks on Monday.
The Russian aircraft were in international airspace but in an area of Nato interest, the RAF said.
The Ministry of Defence said the Russian planes at the weekend "entered the UK's controlled zone of international airspace" off Scotland.
Known as quick reaction alerts (QRAs), such incidents have happened since the Cold War era of the late 1940s to early 1990s.
The RAF say the Russian aircraft pose a risk to civilian flights because of their lack of communication with air traffic control.
Some of the Russian aircraft also trail five mile (8km) long wire antenna behind them, which the RAF say also poses a risk to civilian traffic.
In Monday's QRA, the Blackjacks were flying south towards the UK before turning north.
Norwegian F-16 jet pilots had earlier identified the bombers.
A German surveillance aircraft and an RAF air-to-air refuelling tanker, which is also used by the royal family and prime minister for international flights, were also involved over the course of the QRA.
The Typhoon crews are normally stationed at RAF Lossiemouth in Moray. They have moved temporarily to Leuchars Barracks, a former RAF station, during an upgrade of Lossiemouth's runway.