Two MiG-29 fighter jets from the Polish Air Force intercepted a Russian aircraft which was performing a flight over the Baltic Sea.
The Operational Command of the Armed Forces identified the aircraft as a Il-20 and said it was flying in international airspace.
The Il-20 is a Soviet-era reconnaissance aircraft used for reconnaissance and electronic listening missions.
The air force said that while the Russian plane did not violate Polish airspace, it did not have a flight plan and the transponder enabling it to be tracked was switched off.
"Thanks to the high combat readiness, the professionalism of the pilots and the efficient functioning of the air defence system, the operations were carried out quickly, effectively and safely," Operational Command said in a statement.
The command noted that the Polish Armed Forces remain in constant readiness to respond to any threats and protect Poland's territorial integrity.
Both NATO and the European Union have been on high alert following a string of airspace violations, thought to be from Russia, in recent weeks.
NATO issued a warning to Moscow at the end of September, saying it would use all means to defend against any further breaches of its airspace after the downing of Russian drones over Poland and Estonia's report of an intrusion by Russian fighter jets.
The 10 September incident in Poland was the first direct encounter between NATO and Russia since its full-scale invasion of Ukraine began in early 2022.
Estonia said three Russian MiG-31 fighter jets entered its airspace for 12 minutes on Friday without authorisation, a charge that the Kremlin has rejected.
The incidents caused widespread consternation among leaders across Europe, raising questions about the alliance's preparedness against growing Russian aggression.
"Russia should be in no doubt: NATO and Allies will employ, in accordance with international law, all necessary military and non-military tools to defend ourselves and deter all threats from all directions," the alliance said in a statement.
Following the violation of Polish airspace, NATO Secretary General Mark Rutte announced the formation of the Eastern Sentry programme, which aims to deter further Russian incursions and show solidarity with Poland.
"We see drones violating our airspace. Whether it was intentional or not, it is unacceptable. The allies have expressed full solidarity with Poland. It is crucial to counter aggression and defend every member of the Alliance," the NATO chief said.
Incidents in Denmark and Norway
Meanwhile on 23 September, Denmark's Prime Minister Mette Frederiksen said Russian involvement could not be ruled out after Copenhagen airport was forced to close for several hours the previous night following the sighting of a number of drones.
"It says something about the times we live in and what we as a society must be prepared to deal with," Frederiksen said.
The Kremlin spokesperson Dmitry Peskov called the allegations "unfounded."
Also on 22 September, Oslo airport in Norway was closed for three hours after possible drone sightings were reported.
Russia allegedly violated Norway's airspace three times in 2025, according to the government, but it remains unclear whether Monday's incident was deliberate or the result of navigation errors.
"Regardless of the cause, this is not acceptable," Prime Minister Jonas Gahr Støre said.
