This conflict often gets portrayed as a fight between the Iraqi government and ISIS. That’s overly simplistic on a number of levels: Aside from the Kurds, the Iraqi government has major assistance from Iran and Shia militias. And ISIS didn’t take over a big chunk of Iraq alone.
The Shia militias have to come to play an important —perhaps dangerously important — role in the war against ISIS. The mass defections that plagued the Iraqi army after ISIS’s initial advance decimated its ranks; there are now about 48,000 troops in its official service. The Shia militia members filled the gap: There are now between 70,000 and 120,000 of them in the field.
On the plus side, these militias have been fairly effective against ISIS in front-line combat. ”Everywhere [the Iraqi Army] has won a battle, it’s been either a small-scale engagement ... or it’s been an attack led by the Shia militias,” Michael Knights, the Lafer fellow at the Washington Institute for Near East Policy, said in February 2015.
But they’re also highly sectarian Shia organizations, and ones largely controlled by Iran, to boot. “Let’s call a spade a spade here: The Iranians are running the show,” Phillip Smyth, a University of Maryland researcher whose work focuses on Shia militias, explains.
They’re accused of committing a number of atrocities in Sunni-populated territories they’ve helped liberate, and their very existence both alienates Sunnis from the Iraqi government and empowers Iran, which has an incentive to push Iraqi politics in an (even more) Shia sectarian direction. The more that happens, of course, the harder it will be to deal with one of the key root causes of ISIS’s rise: Sunni grievances with the Shia government.