BERLIN — Chancellor Friedrich Merz suspects the Kremlin is behind most of the drones spotted in German airspace in recent days, forcing the temporary closure of Munich Airport.

“We suspect that a significant portion of it is probably controlled from Russia. But we are investigating the matter, and regardless of where it comes from, it is a serious threat to our security,” Merz said on public television late Sunday.

Drones were sighted around Munich Airport in recent days, forcing authorities to close runways and cancel flights. The cancellations stranded thousands of travelers, many of whom had attended Oktoberfest.

The sightings came amid a wave of drone-related disruptions plaguing Europe’s airspace. European leaders have blamed the Kremlin for violations over Danish, Estonian, Norwegian, Romanian and Polish airspace in separate incidents in recent weeks.

Merz compared the recent violations to incursions into European airspace during the Cold War, but those incidents, he added, did not occur as “frequently as we have been experiencing in recent weeks.”

“These are attempts at espionage,” Merz said. “They are also attempts to unsettle the public. We know that we have to do something about this. We will do so, but we will do so calmly and with a sense of proportion.”

European leaders last week debated a proposal by the European Commission to erect a so-called “drone wall” along the bloc’s eastern flank. Big member states, including Germany and France, however, are reluctant to cede such defense-related matters to the EU, preferring to keep nation-states and NATO in charge.

“We are facing a threat on a scale that we have not seen in recent years,” Merz said. “We are working intensively, including within the European Union and NATO, to reach decisions on how to counter this threat.”

Merz said there’s no evidence that any of the drones spotted thus far have carried weapons. A minority of the incidents, he added, involved people in Germany who were privately building drones in a kind of copycat crime.

A Russian foreign ministry spokesperson ridiculed Merz’s assertion that Moscow is likely behind most of the drone sightings in Germany and beyond.

“Berlin still hasn’t figured out what happened with the streams [Nord Stream pipelines] and still doesn’t know who blew them up,” the spokesperson, Maria Zakharova, said Monday. “It looks like they won’t get around to dealing with drones until the next century.”

Zoya Sheftalovich contributed to reporting.