What role is Iran playing in the Mosul offensive?

Iranian-backed Shiite militias have joined the military campaign to drive the self-proclaimed Islamic State from Mosul, opening a new front to the west of the city as US-backed forces converge from the south and northeast. 

The militias, known collectively as the Popular Mobilization Forces (PMF), seek to secure the western border with Syria, cutting off the pipeline of fighters and supplies connecting Mosul and Raqqa, the de facto capital of ISIS, according to the Associated Press. They say these militias will not enter Mosul itself – an indication that lessons have been learned from previous campaigns to retake cities lost to ISIS.

Jaafar Al-Husseini, spokesman for the Hezbollah Brigades, told the Associated Press Saturday that they and other affiliated militias had advanced about 4 miles toward the town of Tal Afar, destroying three ISIS suicide car bombs with anti-tank missiles as they did.

He added that Iranian military advisors, who arrived in Iraq in August amid preparations for the Mosul campaign, were working with the Iraqi government to get its air support, but said that the US-led coalition was not directly supporting the advance.

The PMF’s entry into the Mosul offensive represents an ongoing convergence of US and Iranian interests in battling ISIS, and comes as general hostility between the two countries has eased somewhat. But some fear that the PMF could infuse the conflict with sectarianism at a time when the US-allied Iraqi military and Kurdish peshmerga are gearing up for a battle that could take weeks or even months.

Past interventions by the Shiite militias have been accompanied by allegations of human-rights abuses of Sunni civilians fleeing the fighting. In June, after the PMF joined the fight to retake Fallujah from ISIS, Human Rights Watch reported that more than a dozen civilians had been executed by militia members, while hundreds of members of a predominantly Sunni tribe were tortured.

"That's why in the beginning [of the offensive] it was stressed by [the Iraqi government] that the operation would be lead by the Iraqi army and the Kurdish Peshmerga forces," Al Jazeera correspondent Jamal El Shayyal told the network from Iraq.

"Now that they have announced an entire frontier led by them, this will cause a lot of concern, especially as there are reports that they are targeting Sunni civilians."

Iran has been involved in the campaign against ISIS since 2014, providing Iraqi military advisers in the battle to retake Fallujah. And Iranian Grand Ayatollah Ali Sistani, based in Iraq, issued a fatwa in the same year calling on able-bodied young men to take up arms against the group, which views Shiites as apostates, as The Christian Science Monitor’s Scott Peterson wrote in June.

Tens of thousands of mostly Shiite men obeyed that call, and since then, Iraq’s militias – backed by Iran – have been instrumental in reversing the IS advance, even in predominantly Sunni areas like Anbar province, where Fallujah is located.”

…

As IS has been pushed back, more than a few of Iraq’s Sunni minority – beneficiaries for decades during the rule of Sunni autocrat Saddam Hussein, but disenfranchised by the American invasion of 2003 – have said they feel more threatened by Shiite forces than by the Sunni IS presence, violent as that has been.

But as Peterson noted in a more recent article on preparing Mosul for a post-ISIS rule, the Iraqi military has perhaps learned to use Shiite militia more judiciously. 

After April 2015, for example, some Shiite militias took part in anti-Sunni revenge attacks during the recapture of Tikrit. By the Fallujah offensive that ended in June 2016, the Shiite militias were kept out of the Sunni city, but were tasked with capturing some outlying towns and oversaw a controversial vetting process of those Sunnis trying to flee for safety, in a bid to catch escaping IS fighters.

As anti-ISIS forces continued their crawl toward Mosul on Saturday, a suicide bomber struck an aid station for Shiite pilgrims in Baghdad, killing at least seven people and wounded over 20. IS claimed responsibility in a statement published by its news affiliate Amaq.