Drone sightings have prompted Sweden to temporarily halt air traffic at Stockholm’s Arlanda airport overnight, police said. Police have launched an investigation into possible airport sabotage, they said in a statement on Monday. Traffic at Arlanda, Sweden’s biggest airport, was halted around 2300 GMT and resumed at 0130 GMT, they added. Daily Aftonbladet quoted an aviation authority spokesperson as saying four drones of varying sizes were sighted from the air traffic control tower.