"The Iranian-backed Iraqi militia targeted by U.S. airstrikes on Sunday was among the Shiite groups that joined in the fight against Islamic State. But for nearly two decades it has also attacked American forces and helped stoke sectarian strife in the Middle East. The deputy commander of the PMF is Abu Mahdi al-Mohandes, who personally advises Quds Force commander Qassem Soleimani. He also heads Kataib Hezbollah, according to policy organizations such as the Counter Extremism Project."