Two NATO members have said Russian drones violated their airspace, as one reportedly flew into Romania during night-time attacks on neighbouring Ukraine while another crashed in eastern Latvia the previous day.

The revelations have led to a severe condemnation of Moscow’s action by NATO and resulted in calls for a joint response from the Western military alliance.

One of the drones reportedly flew into Romania on Sunday during a night-time attack on neighbouring Ukraine, while another crashed in eastern Latvia the day before.

Bucharest dispatched F-16 fighter jets to monitor the skies and issued text warning alerts to the residents of two eastern regions.

Latvia’s defence minister said a Russian drone had fallen near the town of Rezekne on Saturday and was likely to have strayed into the country from neighbouring Belarus, an ally of Russia.

Both countries issued initial incident reports to their NATO allies as fuller investigations were launched.

“This situation is a confirmation that we need to continue the work we have started to strengthen Latvia’s eastern border, including the development of air defence capabilities and electronic warfare capabilities to limit the activities of UAVs [unmanned aerial vehicles] of different applications,” said Andrea Spruds, the Latvian defence minister.

Edgar Rinkevics, the Latvian president, wrote on social media: “We are in close contact with our allies. The number of such incidents is increasing along the eastern flank of NATO, and we must address them collectively.”

A statement issued by the country’s defence ministry said: “Latvian airspace is part of NATO airspace.”

Bucharest condemned what it described as a “renewed violation” triggered by Moscow’s “illegal attacks” on Ukraine.

Fragments of the drone were discovered in an uninhabited area near the Romanian village of Periprava, situated across the Danube river from the Ukrainian port town of Ismail, a frequent target for Russian attacks.

Alliance members on NATO’s eastern flank have had to deal with threats posed by Russian missiles and drones on numerous occasions since Vladimir Putin launched his full-scale invasion of Ukraine in February 2022.

In November 2022, a Russian missile hit Poland, killing two people. Warsaw is also searching its territory for a Russian drone that crashed on its side of the border earlier this summer.

Russian drones have also strayed into Romanian airspace on multiple occasions during Moscow’s bombardment of Ukraine’s Danube ports.

None of the incidents have been deemed significant enough to trigger any of NATO’s collective responses, including its Article Five mutual defence clause, which signifies that an attack on one member is an attack on all.

Mircea Geoana, NATO’s outgoing deputy secretary-general, who is Romanian, said on Sunday: “NATO condemns the overnight Russian airspace violation into Romanian airspace. 

“While we have no information indicating an intentional attack by Russia against Allies, these acts are irresponsible and potentially dangerous.”