Turkish backed FSA has attacked US troops and other coaltion partners (Germany, France etc) in Syria. This is the first time an attack was directed at actual US/EU troops rather then YPG/SDF. Turkey has warned US and other nations that they can get hit by Turkish backed rebels or the Turkish military at any time. The so called coalition in Syria is assisting YPG, a direct affilate of the PKK. The PKK is designated a terrorist group in every coaltion country in Syria. Threat at 1:35 min of video.