Russia warns US its fighter jets are now potential target in Syria

US shooting down of Syrian jet seen as ‘act of aggression’ by Russia, which will track coalition warplanes west of the EuphratesThe threat of direct Russian-American confrontation in Syria escalated on Monday after Moscow said it would treat any plane from the US-led coalition flying west of the Euphrates river as a potential target. Russia said it was responding to US planes shooting down a Syrian air force jet on Sunday. The US said its planes had acted to defend US-backed forces s