Earlier this month, Poland reported more than a dozen drones crossed its border overnight, with some heading toward the strategic hub of Rzeszów. Polish forces, backed by NATO allies, shot down several drones and later also invoked NATO's Article 4. Warsaw called the incident a deliberate Russian provocation.

On Sept. 12, NATO Secretary-General Mark Rutte announced the launch of the “Eastern Sentry” mission to bolster defenses on the alliance’s eastern flank in response to the Russian drone incursion.

Romania has also faced repeated violations, including a drone tracked for nearly 50 minutes in its airspace in mid-September. Fragments from earlier Russian attacks in Ukraine have repeatedly landed on Romanian territory. 

Announcing a new round of EU sanctions on Russian energy and financial transactions on Friday, European Commission President Ursula von der Leyen deplored that in recent days "Russian drones have violated our union's airspace, both in Poland and in Romania."

"Again and again, President [Vladimir] Putin has escalated and in response, Europe is increasing its pressure," she said. "We know that our sanctions are an effective tool of economic pressure, and we will keep using them until Russia comes to the negotiating table."

NATO allies have historically exercised restraint in such situations. The last time a member state shot down a Russian fighter was in 2015, when Turkey downed a Su-24 near the Syria-Turkey border, sparking a sharp diplomatic confrontation with Moscow but no wider conflict.

Since then, despite repeated airspace violations over the Baltics, Poland and Romania, the alliance has refrained from similar moves.

This story has been updated. Paul McLeary contributed reporting from Washington.