Overnight on January 17, ISIS units attacked positions of the Syrian Arab Army (SAA) and its allies south of the Abu al-Duhur airbase from the eastern direction aiming to reach the key village of Sinjar.
Initially, anti-government sources claimed that ISIS had been able to capture some points from the SAA, but these claims were not confirmed by any photo or video evidence yet. Later, the ISIS-linked news agency Amaq confirmed that the advance took place and said that ISIS had captured some positions in the area.
Right now, clashes are ongoing there. Thus, ISIS and “moderate opposition” groups attacking the SAA from the western direction de-facto cooperate against government forces in eastern Idlib.