Putin Warns West as Drones Appear in European Skies

WARSAW—For weeks, drones have been mysteriously appearing in European skies, closing airports from Warsaw to Munich. Western officials suspect that Russia is behind the campaign, seeking to sow fear in European capitals, probe NATO weaknesses and raise the stakes over the continent’s support for Ukraine.

The latest sightings came late Thursday, when Germany closed the Munich airport, grounding 17 departing flights and stranding nearly 3,000 passengers during Oktoberfest. Separately, Belgium said on Friday it was investigating overnight drone sightings above a military base in the east of the country.