The warning follows a projectile striking a passenger terminal at Riyadh Airport on Sunday, a day after a deadly missile attack on the facility by Yemen’s Iran-backed Houthi rebel group killed 13 people.The unidentified projectile struck Terminal 4 at King Khalid International Airport, sparking a fire that killed one person and injured 11, according to Saudi civil aviation authorities.Air defence systems also intercepted a cruise missile near the airport.The Houthis have also warned airlines, passengers and airport staff to stay away from Saudi airports, threatening that “the worst is yet to come” if Riyadh continues its military campaign in Yemen.