WASHINGTON

US President Donald Trump said Thursday that Russia's violations of Polish airspace this week "could have been a mistake" and signaled his displeasure with the incidents.

"It could have been a mistake, could have been a mistake, but regardless, I'm not happy about anything having to do with that whole situation, but hopefully it's going to come to an end," Trump told reporters at the White House as he prepared to depart for New York.

Poland said Wednesday that its airspace was violated by drones amid overnight airstrikes between Russia and Ukraine, defining the incursion as an “act of aggression.” Prime Minister Donald Tusk defined the drones as “Russian,” with authorities initially recording 19 airspace violations.

Warsaw called for an emergency meeting of the UN Security Council and introduced sweeping restrictions on civilian flights along its eastern border with Belarus and Ukraine.

It comes amid heightened security concerns in the NATO member state after Wednesday’s drone incident, which prompted Warsaw to step up coordination with allies.

The Russian Defense Ministry said its drones had carried out a large-scale strike on military targets in western Ukraine but denied any intention to hit Polish territory.

Germany also announced that it will bolster security support for its NATO ally, Poland, in response to recent Russian drone incursions.