The deployment of Iraqi Shi’a militias to Anbar province to support anti-ISIS Iraqi Sunni tribes in combating ISIS is a unique and important dynamic that underscores the desperate need of anti-ISIS Anbari tribes for support.
The acceptance of militia presence in the Sunni heartland was almost certainly the result of the recent increase of targeting of Albu Nimr tribe members by ISIS in Hit district. The militia force was reported to be composed of the Sadrist Peace Brigades of Moqtada al-Sadr, previously known as Jaysh al-Mahdi, which is an artifact of Sadr’s desire to portray the force as a nationalist force that defends all Iraqis. Also, Sadr and his militia have less of a strong relationship with Iran compared to militias such as AAH, the Badr Organization, Kata’ib Hizballah, and others. Therefore, Sadr is more likely to act independently of Iranian strategic objectives in Iraq which are focused on holy sites and strategic terrain in Diyala. Meanwhile, ISIS attacks in Dhuluiya and the use of SVBIEDs in Baiji and near Hit most likely aim to divert the resources of the ISF, militia, and tribes in their anti-ISIS campaign.
Source: The Institute for the Study of War (ISW)