The Syrian Democratic Forces (SDF) warned Turkey on Friday against expanding its military operation against the Kurdish People’s Protection Units (YPG) in Syria, saying it would face the “appropriate response.” Senior SDF official Redur Xelil was responding to Turkish President Recep Tayyip Erdogan’s threat to sweep the YPG from the length of Turkey’s Syrian frontier. He said the operation may widen to Iraq. “When he tries to widen his battle, he will be met by the appropriate response,” Xelil told Reuters in an interview in the town of Amuda in northern Syria. Turkey launched an offensive six days ago against the YPG in Syria’s northwestern Afrin region. It regards the YPG, which is the backbone of the SDF, as a terrorist group. Xelil said he was sure the US-led coalition that has backed the SDF’s battle against ISIS in Syria was trying to put pressure on Turkey to limit its assault. While US-led coalition forces are present in other areas the SDF holds in Syria along the border with Turkey east of Afrin, they are not present in Afrin itself. Turkey considers the YPG to be an extension of the outlawed Kurdistan Workers Party (PKK), which has waged a three-decade-long insurgency in Turkey’s largely Kurdish southeast.