Munich Airport was forced to suspend operations late Thursday night after multiple drone sightings disrupted air traffic, grounding flights and stranding thousands of passengers in what has become a growing challenge for European aviation hubs.

The airport said 17 departures were halted shortly after 10 p.m. local time, affecting nearly 3,000 passengers, while 15 incoming flights were diverted to Stuttgart, Nuremberg, Vienna, and Frankfurt. “When a drone is sighted, the safety of travelers is the top priority,” airport authorities said in a statement.

The incident follows similar disruptions last week, when drone activity temporarily shut airports in Denmark and Norway. In Denmark’s case, Prime Minister Mette Frederiksen stopped short of naming a culprit but said, “we can at least conclude that there is primarily one country that poses a threat to Europe’s security – and that is Russia.”

Munich had already been on heightened alert earlier this week after a bomb threat briefly interrupted Oktoberfest celebrations and explosives were discovered in a residential building in the city’s north.

The airport, a Lufthansa hub and one of Europe’s busiest, handled nearly 20 million passengers in the first half of this year.

The latest disruption comes amid broader European concerns over repeated drone sightings and alleged Russian incursions into NATO airspace in Poland and Romania, as well as violations of Estonian airspace by Russian fighter jets. On Wednesday, EU leaders endorsed new measures to bolster the bloc’s defenses against drone threats.

Responding to the accusations, Russian President Vladimir Putin on Thursday quipped that he would “no longer fly drones over Denmark,” while Moscow has formally denied involvement in any of the incidents.