It seems that the conflict between the armed groups has already started, and they are competing with the army for presence on the ground. On May 26, Maki al-Nazzal, a prominent Fallujah figure, said in a press statement, “The disputes between the Sunni tribal forces and the [PMU] culminated May 25 when the latter burned houses after looting them upon the advance of Iraqi troops in the Shahabi area north of the city.”
The Sunni regions now have several armed forces such as the Sunni tribal forces fighting in Anbar and Salahuddin alongside the Iraqi security forces, the National Mobilization Forces that are preparing for the Mosul battle led by former Ninevah governor Atheel al-Nujaifi, and the recently formed Ninevah Forces. This plurality might create a conflict among armed Sunni groups.
The Iraqi army is no longer the only armed force in Iraq. The Kurdish peshmerga is handling security in the Iraqi Kurdistan Region and other disputed areas. The peshmerga has fought with the Iraqi army many times in disputed regions on the administrative borders between the federal Iraqi government and the Iraqi Kurdistan Region. The PMU are handling security in the south of Baghdad, while the Sunni tribal forces will take control of the liberated regions.
Nobody knows the fate of those armed forces after IS. Will they fight with the Iraqi army over the control of the security situation in Iraq, or will they be part of it?