BEIRUT - US-backed Syrian militias said Russian jets and Syrian government forces struck their positions in Deir al-Zor province on Monday, killing and injuring a number of fighters. There was no immediate comment from Moscow or Damascus. The Syrian Democratic Forces, an alliance of Kurdish and Arab militias, said they came under attack near a major gas field they had seized from Islamic State in recent days. 'We will not stand by with our arms crossed and we will use our legitimate right to self-defence,' said the statement by the SDF, which fights alongside the US-led coalition.