Poland said Wednesday that, along with NATO allies, it had scrambled warplanes to shoot down multiple Russian drones that entered its airspace during Moscow’s latest attack on Ukraine, calling the incident an “act of aggression.”

“Last night the Polish airspace was violated by a huge number of Russian drones,” Prime Minister Donald Tusk said in a social media post. “Those drones that posed a direct threat were shot down. I am in constant communication with the Secretary General of NATO and our allies.”

Poland’s military said it scrambled aircraft to shoot down “hostile objects” in Polish airspace, a first for a NATO country during the war. The military, in a post on X, called it “an unprecedented violation of Polish airspace by drone-type objects” and an “act of aggression that posed a real threat to the safety of our citizens.”

The European Union’s top diplomat, Kaja Kallas, said early indications suggested the Russian drone incursion into Poland’s airspace was intentional.

“Last night in Poland we saw the most serious European airspace violation by Russia since the war began, and indications suggest it was intentional, not accidental,” Kallas said in a statement. “The EU stands in full solidarity with Poland. Russia’s war is escalating, not ending. We must raise the cost to Moscow, strengthen support for Ukraine, and invest in Europe’s defense.”

Russia’s Ministry of Defense said its drones had not targeted Poland, but Moscow’s close ally, Belarus, said it tracked some drones that “lost their course” after being jammed, according to The Associated Press. Polish officials have said some of the drones were launched from Belarus, which Russian forces have used as a base for both ground and aerial attacks on Ukraine throughout the war.

In a statement posted on social media, a NATO spokesperson said fighter jets from the Netherlands were deployed and helped to shoot down the drones, confirming it was “the first time NATO aircrafts have engaged potential threats in Allied airspace.”

In addition to the direct response by Polish and Dutch fighter jets, German Patriot missiles based in Poland “were placed on alert,” and an Italian airborne early warning aircraft and a NATO refueler aircraft were also launched, according to the statement from NATO spokesperson, Col. Martin L. O’Donnell.

“NATO responded quickly and decisively to the situation, demonstrating our capability and resolve to defend Allied territory,” Gen. Alexus G. Grynkewich, NATO’s commander for Europe, said in a statement shared with CBS News.

“My thanks and congratulations to the Polish Operational Command and our NATO pilots for shooting down Russian drones over Poland,” Poland’s Prime Minister Tusk said in a later social media post. “Actions speak louder than words.”

“We stand by our NATO Allies in the face of these airspace violations and will defend every inch of NATO territory,” U.S. Ambassador to NATO Matthew Whitaker said Wednesday in a social media post, in the first reaction from a senior American official to the Russian incursion into Poland’s airspace.

Apparent Russian drones and missiles have entered the airspace of NATO members previously, including Poland’s, several times during Russia’s three-and-a-half-year war, but no NATO country had ever tried to shoot them down.

A cornerstone of the Western NATO military alliance is the principle that an attack on any member is considered an attack on all. A NATO source told the Reuters news agency that the alliance wasn’t treating the Russian drone incursion into Polish territory as an attack, but that it did appear to have been deliberate.

Tusk told Poland’s parliament that authorities had identified 19 violations of the country’s airspace overnight and shot down at least three drones, adding that no one was harmed in the “Russian action.”

Tusk said Poland had made a “formal request to invoke Article 4” of the NATO alliance’s founding treaty. Under Article 4, any member can call urgent talks when it feels its “territorial integrity, political independence or security” are at risk.

The Polish case marked the eighth time the article has been invoked since the alliance was founded in 1949, and the third time Article 4 has been invoked to address Russia’s incursions into and invasion of Ukraine. 

NATO’s collective security is based on its Article 5 principle, which states that if one member is attacked, the entire alliance will come to its defense. That article has only been invoked once in the history of NATO, by the United States, following the Sept. 11, 2001, terrorist attacks.

Poland’s military said efforts were “underway to search for and locate the possible crash sites of these objects” and “the Operational Command of the Polish Armed Forces is monitoring the current situation, and Polish and allied forces and assets remain fully prepared for further actions.”

Polish police said officers had discovered a damaged drone in the eastern Polish village of Czosnowka, according to Reuters, and there were reports that a building was damaged by a falling drone or debris in another eastern Polish town, but there were no reports of any injuries.

Hours later, Poland’s military said on X that the operations had concluded but the search for downed drones was continuing. “We urge that in the event of observing an unknown object or its debris, do not approach, touch, or move it. Such elements may pose a threat and contain hazardous materials. They must be thoroughly inspected by the appropriate services,” the military cautioned.

The Polish government announced it would hold an “extraordinary” meeting Wednesday morning.

The incursion came as Russia unleashed a barrage of strikes across Ukraine, including in the western city of Lviv, around 50 miles from the Polish border.

Warnings of further Russian aggression

Ukrainian President Volodymyr Zelenskyy said Wednesday that eight Russian drones were “aimed toward” Poland in an overnight barrage that forced Warsaw to scramble air defenses. “It was not just one Shahed that could be called an accident, but at least eight strike drones aimed toward Poland,” Zelensky said, referring to Iranian-designed drones deployed by Moscow, adding that the incident represented “An extremely dangerous precedent for Europe.”  

Ukraine’s foreign minister, Andriy Sybiga, warned on X that Russian President Vladimir Putin “just keeps escalating, expanding his war, and testing the West. The longer he faces no strength in response, the more aggressive he gets. A weak response now will provoke Russia even more — and then Russian missiles and drones will fly even further into Europe.”

Poland’s newly-elected nationalist President Karol Nawrocki issued a warning along the same lines Tuesday, saying at a news conference in Helsinki that, “We do not trust Vladimir Putin’s good intentions. We believe that Vladimir Putin is ready to also invade other countries.”

European Union chief Ursula said Moscow had carried out a “reckless and unprecedented” violation of Polish airspace.

And the EU’s top diplomat, Kaja Kallas, posted on X Wednesday that “we saw the most serious European airspace violation by Russia since the war began, and indications suggest it was intentional, not accidental. The EU stands in full solidarity with Poland. Russia’s war is escalating, not ending.”

NATO-member Poland, a major supporter of Ukraine, hosts over a million Ukrainian refugees and is a key transit point for Western humanitarian and military aid to the war-torn country.

Last month, Warsaw said a Russian military drone flew into its airspace and exploded in farmland in eastern Poland and depicted the incident as a “provocation.” In 2023, Poland said a Russian missile had crossed into its airspace to strike Ukraine. And in November 2022, two civilians were killed when a Ukrainian anti-aircraft missile fell on a village near the border.