Russia said on Monday it would treat US-led coalition aircraft flying west of the River Euphrates in Syria as potential targets and track them with missile systems and military aircraft, but stopped short of saying it would shoot them down. In a move that will fan tensions between Washington and Moscow, Russia made clear it was changing its military posture in response to the US downing of a Syrian military jet on Sunday, something Damascus said was the first such incident since the start of the country's conflict in 2011. The Russian Defence Ministry said it was also scrapping a Syrian air safety agreement with Washington designed to avoid collisions and dangerous incidents with immediate effect. Moscow accused the United States of failing to honour the pact by not informing it of the decision to shoot down the Syrian plane despite Russian aircraft being airborne at the same time.