The U.S.-led coalition airstrikes on Monday killed and wounded 150 militants from Sayyed al-Shuhada' Battalions, an Iran-backed Shiite group, while they were crossing the Iraqi border to northeastern Syria, according to the militia's statement.
The key unit of the Popular Mobilization has demanded the Iraqi government to investigate in the 'mean' attack, accusing Washington of hindering the battle against the Islamic State (Daesh).
Monday's Strikes were the second direct response for the U.S. against pro-Assad militias.
Last May, the U.S. warplanes launched airstrikes on the regime forces who were near the Jordanian border and deemed a threat to coalition partners on the ground, Fox News cited a Pentagon official.
They were repeatedly ordered to stop their advance toward a de-escalation zone, but ignored the warning, officials said.
