Poland said Wednesday that Russian drones breached its airspace overnight during a large-scale strike on western Ukraine, an escalation that Warsaw called an "unprecedented violation" and a serious test for NATO.

Polish Prime Minister Donald Tusk said his military recorded 19 incursions, four of which were destroyed by Polish and NATO air defenses. "I have no reason to claim we're on the brink of war, but a line has been crossed," Mr. Tusk told lawmakers. "This situation brings us the closest we have been to open conflict since World War Two."

The incident marked the first time Poland has used its air assets against intrusions since Russia's full-scale invasion of Ukraine began in 2022. NATO Secretary General Mark Rutte confirmed that "numerous drones entered Polish airspace overnight and were met with Polish and NATO air defenses," calling the breach "reckless behavior."

Several airports, including Warsaw Chopin, briefly closed as the drones flew over eastern regions. The Polish military labeled the incursions an "act of aggression," urging civilians to shelter in place before declaring airspace secure. NATO later said Dutch F-35s were scrambled in support of Polish forces.

Ukrainian officials said the drones were part of a "massive" Russian barrage targeting critical infrastructure. Foreign Minister Andrii Sybiha accused President Vladimir Putin of "testing the West" and urged partners to strengthen air defenses and accelerate sanctions. President Volodymyr Zelenskyy said eight Russian drones entered Polish territory, calling it "an extremely dangerous precedent for Europe."

Moscow denied responsibility. Kremlin spokesman Dmitry Peskov dismissed the allegations, saying EU and NATO leaders accuse Russia of provocations "on a daily basis." Russia's defense ministry said it had no targets in Poland and suggested the drones "lost their way." Belarus, an ally of Moscow, claimed it also shot down several drones that crossed its border.

European leaders swiftly condemned the breach. European Commission President Ursula von der Leyen described the incursion as "reckless and unprecedented," urging "more sanctions" and vowing that Europe "stands in full solidarity" with Warsaw. French President Emmanuel Macron called the violation "simply unacceptable," while Hungarian Prime Minister Viktor Orban, often aligned with Moscow, said "the violation of Poland's territorial integrity is unacceptable."

The United States also voiced support. "We stand by our NATO Allies in the face of these airspace violations and will defend every inch of NATO territory," said Matthew Whittaker, U.S. Ambassador to NATO.