Russian jets engaged in "unsafe and unprofessional behavior" while taking part in a mission against Islamic State in Syrian airspace, U.S. Air Force says. Moscow accused them of violating the airspace of a joint training area. Russian drones fired flares in front of drones, forcing them to conduct "evasive maneuvers," Moscow says. Earlier this year, the United States said a Russian fighter jet caused a U.N. drone crash over the Black Sea, but Moscow denied responsibility for it.