At least seven flights and a cruise ship in Europe received bomb threats on Tuesday, causing disruption at airports, and no devices were discovered.

Two flights to Warsaw, two to Sofia, two to Rome and one to Murcia airport in Spain were targeted; an airport in Warsaw was briefly shut and the Italian Air Force accompanied one of the flights to Rome. The UK government described the incidents as “malicious hoax threats,” and authorities from various countries will cooperate to assess whether this was a coordinated action designed to disrupt airspace. The Panama-flagged cruise ship Crown Iris, preparing to depart the Greek port of Syros for Haifa, was searched by a bomb disposal team and had 940 passengers and 597 crew members on board. According to Greek media, the captain received a warning directly by radio saying that an explosive device had been placed on the hull below the waterline; an initial search found no suspicious objects, and a second, more thorough inspection by the Coast Guard’s underwater missions unit was expected.