Estonia has requested a consultation with other Nato members after Russian warplanes violated its airspace on Friday morning.
Three Russian MiG-31 fighter jets entered the Estonian skies “without permission and remained there for a total of 12 minutes” over the Gulf of Finland, the government said.
Italy, Finland and Sweden scrambled jets under Nato’s mission to bolster its eastern flank. A Nato spokesperson said it was “yet another example of reckless Russian behaviour and Nato’s ability to respond”.
Russia denied violating Estonian airspace. But tensions have been escalating recently, after Poland and Romania – both Nato members – said Russian drones breached their airspace.
Article 4 of the Nato treaty formally starts urgent consultations within the 32-member alliance, which ties the US and many European nations together on collective defence.
It is the second time this month that a Nato member has requested Article 4 consultations. Poland did so on 10 September after Russian drones entered its airspace.
Estonian Prime Minister Kristen Michal said “Nato’s response to any provocation must be united and strong”.
“We consider it essential to consult with our allies to ensure shared situational awareness and to agree on our next joint steps,” Michal said.
US President Donald Trump said on Friday: “I don’t love it. I don’t like when that happens. Could be big trouble.”
Estonia, which shares a border with Russia to the east, says this was the fifth Russian violation of its airspace this year.
Officials said the Russian aircraft entered its airspace from the north-east and were intercepted by Finnish jets over the Gulf of Finland. Once inside Estonian airspace, Italian F-35 jets, based in Estonia, were deployed under Nato’s Baltic Air Policing mission to escort the aircraft out.
The government said the Russian jets had no flight plans, had their transponders turned off and also did not have two-way radio communication with Estonian air traffic control.
Russia’s defence ministry said the jets were on a “scheduled flight… in strict compliance with international airspace regulations and did not violate the borders of other states, as confirmed by objective monitoring”.
It said they flew over neutral Baltic waters, more than 3km (two miles) from Vaindloo Island, which belongs to Estonia.