Poland is sounding the alarm. Its leaders want NATO to consider a tough new response: a no-fly zone over Ukraine. The proposal follows a wave of Russian drone incursions into Polish airspace, an event that raised security fears across the alliance.

Multiple Russian drones crossed into Poland in what European officials described as a deliberate provocation, causing NATO to send fighter jets to shoot them down.

Polish fighter jets, with help from NATO allies, shot down multiple Russian drones that entered its eastern border early on Sept. 10. It was the first time the NATO member directly engaged with Russian military assets in its airspace since Moscow's invasion of Ukraine in 2022.

Military officials in Poland say the country's airspace was "repeatedly violated by drone-type objects" in the overnight hours amid Russian strikes on targets in Ukraine.

Article 4 allows member states to start a formal discussion within the alliance about threats to their security. It does not commit the alliance to military action.

The U.S.-led military alliance said it would bolster defenses along its eastern flank after the incursion, the first of its kind since the Ukraine war began; Russia denied targeting Poland.

NATO allies Poland and Romania both scrambled fighter jets to respond to Russian drone and missile attacks in Ukraine on Saturday.

NATO is preparing a defensive military response to the drone incursion in Poland to strengthen deterrence across the alliance’s eastern flank, according to a person familiar with the matter.

After multiple Russian drones violated NATO airspace, Europe faces questions over the alliance’s long-term ability to deal with this growing threat.