Key Facts

• At least four Ryanair flights were among those targeted, making the airline the most affected.
• Warsaw airport was temporarily closed after two threats involving flights bound for the Polish capital.
• London police reported threats against four aircraft due to depart from or arrive at Heathrow, plus a warning about a flight at Manchester Airport.
• Threats affected flights involving airports in Spain, Italy, Poland, Portugal, Ireland, Bulgaria, Denmark and the United Kingdom.
• Italian air force jets escorted a Ryanair flight from Dublin as it landed at Rome-Fiumicino.
• Authorities reported that searches found no explosives, and the planes landed safely.
• A flight-threat adviser listed copycat threats, one person or group issuing multiple threats, and state-linked hybrid warfare as possible explanations; the incidents' source remained unknown.