A woman looks at damages at the site of a car bomb attack in Baghdad’s Sadr City , December 5, 2014.

The Islamic State of Iraq and Syria (ISIS) group on Friday claimed it carried out a suicide bombing south of Baghdad that targeted Sunni fighters who oppose the militants, in which 38 people were killed.

The bomber attacked the fighters, known as Sahwa, while they were gathering near a military base in Madain on Wednesday to receive their pay, also wounding at least 56 people.

ISIS claimed the attack in a message posted online titled “Statement on the Martyrdom Operation in the Madain District”, and identified the bomber as Saifeddin al-Ansari.

ISIS spearheaded a sweeping militant offensive that has overrun much of Iraq’s Sunni Arab heartland since June — areas that Shiite-led government forces have sought local Sunni help to recapture.

The Sahwa, or “Awakening” in Arabic, dates back to the height of the U.S.-led war in Iraq, when Sunni tribesmen joined forces with the Americans to battle insurgents including ISIS’ predecessor organization, the Islamic State of Iraq.

The Sahwa were key to greatly but temporarily reducing the violence, but when Iraq’s government took over responsibility for their salaries they were sometimes paid late or not at all.

Now Sunni fighters, including the Sahwa and other armed tribesmen, again have an important role to play in the fight against ISIS.

The government has distributed arms and ammunition to tribesmen, and Prime Minister Haider al-Abadi aims to establish a national guard made up of local fighters, although the necessary law has yet to pass parliament.

Iraqi security forces backed by U.S.-led air strikes, Kurdish forces, Shiite militias and Sunni tribesmen have clawed back some ground from ISIS.

But major areas, especially north and west of Baghdad, remain outside government control.

[wpResize]