The EU’s foreign policy chief on Sunday slammed Moscow’s “reckless escalation” after a Russian drone breached Romanian airspace during an attack on southern Ukraine.

“The violation of Romanian airspace by Russian drones is yet another unacceptable breach of an EU Member State’s sovereignty,” Kaja Kallas said on social media platform X. “This continued reckless escalation threatens regional security.”

Europe’s eastern borders were already on high alert after NATO forces shot down 19 Russian drones that invaded Poland’s airspace last Wednesday.

On Saturday, two Romanian F-16 fighter jets spotted a Russian drone over Romanian territory while doing a scouting exercise to monitor Russian airstrikes across the border in Ukraine.

Romania’s foreign minister slammed the incursion as “unacceptable and reckless.” No damage or injuries were reported, Romania’s defense ministry said in a statement.

“We stand in solidarity with Romania,” Kallas said. “I am in close contact with the Romanian government.”

In the previous Russian incursion into Poland, five drones had been on a direct flight toward a NATO base before being intercepted by Dutch Lockheed Martin F-35 fighter jets.

The incursion in Poland left no damage. But the incident exposed the transatlantic alliance’s poor planning for handling drones, which have emerged as a central element in modern warfare during the conflict in Ukraine. In the latest encounter, NATO forces used equipment worth billions of dollars to counter Russian drones that were made of wood and foam.