NATO has intercepted two Russian jets near the Finnish border with Norway.
The Kremlin aircraft were spotted off the coast of Finnmark, in the north of Norway, by two F-35 fighter planes.
The Mikoyan MiG-31 'Foxhound' and Sukhoi Su-24 'Fencer' retreated east after being intercepted by Norway's jets.
It comes amid rising tensions between Russia and Scandinavia after Sweden and Finland vowed to join NATO.
The Royal Norwegian Air Force tweeted: "F-35 identified two Russian aircraft north of Finnmark today.
"CRC (Control and Reporting Centre) Sørreisa (in Finnmark) reported the aircraft, and NATO ordered our F-35s on their wings.
"The Russian aircraft flew to the Norwegian Sea before returning east. F-35 is on permanent readiness for Norway and #NATO. #WeAreNATO #f35"
Stine Barclay Gaasland, spokesman for the Norwegian Air Force, said the Russian jets could have provoked 'more aggressive action' if they entered Norway's airspace, The Sun reports.
The Royal Norwegian Air Force always has two F-35 fighters on standby as part of NATO's Quick Reaction Alert.
Russia's invasion of Ukraine, which it calls a "special operation", has highlighted Sweden and Finland's vulnerabilities despite their close cooperation with NATO in recent years.
Finnish President Sauli Niinisto confirmed his country would submit an application for the military alliance in a historic policy shift prompted by the invasion.
Moscow, which shares an 800 mile border with Finland, said it would be a mistake for Helsinki to join the transatlantic alliance and that it would harm bilateral ties.
Meanwhile, public support for membership has grown in Sweden due to security concerns.
Earlier this month Mr Niinisto called Putin to tell him of Finland's plans to join the alliance.
Putin said such a move would hurt Russian-Finnish relations.
"I, or Finland, are not known to sneak around and quietly disappear behind a corner. It is better to say it straight what already has been said, also to the concerned party and that is what I wanted to do," he said about his call.
Sweden, which shares a maritime frontier with Russia, is also set to apply to join the organisation.
NATO Secretary-General Jens Stoltenberg previously said it would be possible to allow Finland and Sweden to join "quite quickly".
Kremlin spokesman Dmitry Peskov warned that the steps taken by Finland to join NATO were a cause for regret and a reason to impose a symmetrical response.
Downing Street said the UK would support the two nations’ “democratic wish” to try to join Nato.
It comes after Russia confirmed it will take precautionary measures if NATO deploys nuclear forces closer to its borders, according to the country's deputy foreign minister.
