BAGHDAD — Factions affiliated with the Popular Mobilization Units have taken part in the operations to liberate Fallujah launched on May 23 in support of the Iraqi security forces. However, some of the forces fighting under the group's umbrella have well-known relations with Iran through the Quds Force and its commander Qasem Soleimani, who has been in Iraq since the Islamic State (IS) took over the city of Mosul June 10, 2014.

Some of the Iraqi Sunni forces have been against the participation of the Popular Mobilization Units in the battle to liberate Fallujah, protesting that the militia would commit human rights violations as it had done last year in the city of Tikrit in the Salahuddin province.

Although this rejection might be based on sectarian concerns, there have been reports and evidence of these violations.

Iraqi activists posted videos online showing the group's forces attacking civilians in Fallujah. A video posted by Sunni activists on YouTube showed a man wearing a military uniform beating a group of civilians with a rod, commanding them to proclaim that the “people of Fallujah are cowards.”