Shiite militias in Iraq begin to remobilize

But analysts say that the absence of a major militant group on the Shiite side had prevented the violence from escalating into all-out war — until now.

“The big dynamic we are dancing around is this move back into civil war, triggered by the Islamic State,” said Toby Dodge, a professor at the London School of Economics. “For a while there wasn’t the second hand to do the clapping, and now there is, and that’s Asaib Ahl al-Haq.”

Formed in 2006, Asaib Ahl al-Haq was responsible for frequent bombings targeting U.S. forces during the Iraq war. Now members say its priority is ISIS.

“You have this computer system, and this whole system was infected with a virus,” said Abu Sajad, referring to ISIS’s prevalence in Iraq. “You have to import something to deal with that, that’s what we are for.”