Tal Afar, near Mosul -  When Islamic State fighters withdrew from Tal Afar airport last week, they left behind a place that was little more than a vast field of explosive-rigged rubble. No building remains standing and burned out vehicles dot the ruined strips of tarmac linking dug-in defensive positions.

ISIL's retreat before the coalition of mainly Shia militias known as the Popular Mobilisation Units (PMU) (al-Hashad al-Shaabi), left a runway that looks as if it will never again see a plane and dozens of booby-trapped IEDs.

ISIL fighters didn't go far, withdrawing only the two kilometres to Tal Afar itself, within easy sight and weapons range. Small clouds of smoke from incoming mortar strikes mushroomed up around the airfield as PMU pickups moved along cleared access roads on Sunday afternoon.

Fighters exchanged machinegun fire at the end of the runway closest to the city, while three men clutching radios took cover behind a collapsed building and tried to locate a sniper targeting them. Shortly after came the repeated whistle of outgoing artillery fire passing overhead.

An armoured suicide car bomb, one of ISIL's most devastating weapons, began moving towards their position, but quickly turned back, the driver seemingly deciding he would not be able to breach their defences.

In response to news of retaking Tal Afar airport by PMUs, the mukhtar, or mayor, of a village just outside Tal Afar which is still occupied by ISIL, said: "Living under ISIL is hell. We don't care who comes; the army, Peshmerga, the PMUs, we just want to be free".

Roads eventually become dry mud and the last 30km to the airport cuts through a virtual moonscape of fine dust  that plumes from wheel arches cutting visibility to metres  [John Beck/AlJazeera]

In a dramatic development on Wednesday, ISIL's last supply line from Mosul to Syria was severed by Iraqi-led forces, leaving the armed group's stronghold completely isolated. PMU fighters captured the road linking Tal Afar to Sinjar, west of Mosul, and linked up with Kurdish forces there, according to Iraqi security officials. Taking over Tal Afar itself completes the encirclement of Mosul and denies ISIL fighters any chance of reinforcements.

Living under ISIL is hell. We don't care who comes; the army, Peshmerga, the PMUs, we just want to be free.

A village mayor, outside Tal Afar

Tal Afar itself is small, with a pre-ISIL population of only 200,000. It has fallen to as low as 100,000. But the future of this Turkmen-majority city and the actions of the PMUs could alter the outcome of the six-week long offensive to retake Mosul, 60km to the east.

Comprised mostly of Shia militias, but also including Sunni groups and others, the PMU was officially designated part of the Iraqi armed forces in February 2016, after it took centre stage in the fight against ISIL in 2014.

Iraqi armed forces are pressing on Mosul, ISIL's last significant urban stronghold, from three sides. But commanders left the expanse of desert between it and the Syrian border open at first, seemingly to allow ISIL fighters an escape route back to Syria and to spare Mosul residents the worst of the fighting.

The PMU, however, filled the gap with an offensive announced on October 29. They moved fast, pushing northwest from the city of Qayyara. There is no doubt who holds power here. The road is lined with flags of its different member factions, including Badr Organisation, Asaib Ahl al-Haq, Kata'ib al-Imam Ali, al-Abbas brigade and Kata'ib Hezbollah, variations in green and yellow of swords, maps and - inspired by Lebanese Hezbollaa's motif -  an outstretched hand clutching a Kalshnikov.

Most of these groups were trained and backed by Iran and, despite official oversight from Baghdad, maintain loyalty to Tehran's supreme leader Ayatollah Ali Khamenei.

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The PMU excel at mobile warfare, but the push on Tal Afar has been long. Roads from Qayyara are scored with deep gashes every few metres, a standard ISIL delaying tactic, and holes where IEDs have been dug out are almost as regular.

After about 50km, tarmac gives way to gravelled paths through power line-studded desert linking a series of small settlements of mud-bricked houses and dry trees. This stretch of desert next to the Syrian border that the road to Tal Afar leads through, was once a stronghold of both ISIL and its precursor organisations.

Residents have fled now, with coils of razor wire and gun trucks signalling the presence of sporadic groups of PMU fighters in their place.

Roads eventually become dry mud and the last 30km to the airport cuts through a virtual moonscape of fine dust several inches thick that plumes from wheel arches and rear bumpers cutting visibility to just metres even at noon. Tyre tracks are the only indication of the path between sporadic tents, checkpoints and communications lorries.

Along this route stream an endless variety of pickups, flatbed lorries piled high with supplies and hulking fuel tankers. Fighters crowd on to all of them, clutching Kalashnikovs and wearing balaclavas with winter jackets to protect against the dust.

Underneath, the men are dark tanned and unlike clean-shaven Iraqi forces, many sport beards with their mismatched fatigues. Most are a long way from home, but morale remains high and they blast religious songs, shout and smile on their way to battle.

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The PMU's role in the Mosul operation has been controversial.

Human rights groups have documented violations committed by PMU members, including the abduction, killing and torturing of civilians in past operations to retake territory from ISIL. The presence of the units in a majority Sunni area risks furthering sectarian divisions and even provoking Turkish involvement. 

Despite PMU's prominent roles in previous offensives against ISIL, Baghdad deliberately and publicly excluded them from moving on Mosul in an effort to minimise any sectarian element of the battle for the largely Sunni city.

Nisham, a Turkman from Tal Afar in his 20s, who now lives in an IDP camp outside Mosul, warns that the advance of the PMU could risk exacerbating deep pre-existing tensions. "There will be a sectarian war there," he warned. 

Tal Afar saw some of the worst of Iraq's sectarian bloodshed with death squads on both sides. When ISIL overran the area in 2014, it destroyed Shia mosques and executed dozens of men. Now, many residents and local Sunnis worry of a PMU quest for vengeance.

Should this come to pass, the situation could be further complicated by Turkey which has discovered a newfound sympathy for Tal Afar's Turkmen.

President Recep Tayyip Erdogan has threatened to intervene if the PMU "terrorises" Tal Afar and currently has troops massed at Silopi near the tripoint with Iraq and Syria. The PMU operation was, as a result, an unwelcome development to governments in Baghdad and Erbil, as well as the US-led anti-ISIL coalition.


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But PMU leaders have attempted to assuage some of these concerns, with former Transport Minister Hadi al-Amiri's Badr Organisation quickly taking a lead and providing a level of acceptance from the government in Baghdad that the PMU did not enjoy.

Local Turkmen leaders have urged Baghdad to allow only army or police forces to enter Tal Afar in accordance with pledges by Iraqi Prime Minister Haider al-Abadi. But at the airport, commanders described plans to move on the city soon.

There, a local operation commander and Badr member who goes by the nickname Abu Ali al-Nasri said the PMU had taken the airport in just six hours, catching ISIL off guard and killing 15 of its fighters. Kata'ib Hezbollah had led the assault, another fighter said, while Iranian advisers had been present, the commander confirmed.

A commander and Badr member nicknamed Abu Ali al-Nasri said the PMU had taken the airport in just six hours, catching ISIL off-guard and killing 15 of its fighters [John Beck/AlJazeera]

Nasri said preparation had already begun to move on the city itself and that his men had now surrounded it from three sides, sending foreign ISIL fighters fleeing, along with their families, to Syria. His men would soon complete the encirclement, he added, cutting off ammunition and support from the Syrian side.

Some PMU fighters feel that they have been unfairly portrayed and rankle at the term "militia". Another senior Badr commander, who introduced himself as Abu Mohammed al-Attabi, sought to assuage concerns, pledging that Tal Afar's civilians would be protected. "Some think we have revenge in mind, but people can see from our treatment that is not the case," he said.

Battle for Mosul: Heavy fighting in Tal Afar as Iraqi forces advance

Despite recent rhetoric, Michael Knights, an Iraq specialist at the Washington Institute, predicts that the PMU may in fact be satisfied in having proved their relevance and strength to Baghdad by encircling Tal Afar and allow the Iraqi army to finish the extremely tough urban fighting that awaits them in the town.

If they do decide to move in, however, Knights warns that the standards of behaviour to which they hold themselves and the nature of the groups involved will be crucial.

The presence of more openly sectarian elements could provoke fear and resentment from majority Sunni Mosul residents or incite Turkey into a cross-border action. The ultimate success of the Mosul campaign may depend on it.

Source: Al Jazeera