Several SPG-9 rifles and other weapons were found in hastily dug holes when Iraqi forces exploring the steep sides of the mountainous terrain spotted the loose soil used to cover the arms.

Three IS militants were killed the day that Al-Monitor accompanied the forces, according to an officer on the front, while two members of the local police force were injured.

Officers on the front told Al-Monitor that at least 50 armed IS fighters were estimated to be in the area.

On Dec. 25, the third day of the operation, Al-Monitor accompanied local police, a regional SWAT team and fighters from mostly local Popular Mobilization Units (PMU) into the mountains to root out IS members hiding in tunnels and caves.

HAMRIN MOUNTAINS, Iraq — Two weeks after Prime Minister Haider al-Abadi declared victory against the Islamic State (IS), Iraqi joint forces began an operation to clear out remnants of hideouts in the mountainous terrain in the northern Salahuddin province.

After leaving before dawn from the nearby town of al-Alam, the local police unit stopped along the road to pray and eat a few dates for energy prior to sunrise. They then moved toward the mountains along a road flanking the Albu Ajil and Alas oil fields.

Flames from oil wells, first set alight in March 2015 by IS in an attempt to ward off air attacks, brightened the landscape.

A regional SWAT team met up with the local police with whom Al-Monitor was traveling. Team members said “resistance” had been found along the road and cradled their guns out of half-opened vehicle windows. After passing through the mountain chain, we were in a higher altitude plain in adjacent Kirkuk province; this is where Hawija and surrounding agricultural villages were freed from IS in early October.

While a black IS flag still flew high over the pass, written on it were the words “Ya Hussein,” an invocation to the Prophet Muhammad's grandson Hussein ibn Ali, who is revered by Shiite Muslims.

Salahuddin is a mainly Sunni province, but local Shiite PMUs were instrumental in freeing it from IS.

Leaving the vehicles in the foothills of the low-lying mountain chain, with some men stationed next to mortar positions, the forces spread out on foot. Several hours later, after two men from the local police had been injured by shooting from IS fighters said to have been hiding in a tunnel, the forces explored an area over which helicopters had been seen circling. On arriving near the area of impact, two vehicles were found: one with a Salahuddin license plate and another without any license plate and with rusty munitions stacked in the back.

IS often booby-traps vehicles, but Al-Monitor was told the vehicles had likely been abandoned hastily due to aircraft overhead and the impracticality of advancing farther by vehicle.

While the vehicles were being searched, a man inexplicably opened fire on them. Shouting ensued, and Al-Monitor and others left the immediate vicinity because of the potential danger of the munitions' exploding. Once far enough away to be relatively safe, fighters began yelling about why the man might have done this. He had subsequently moved away in the opposite direction.

Brig. Gen. Mohammed Al-Hamash, the al-Alam local police commander, told Al-Monitor that the man was from the “southern PMU” and that he was only an ambulance driver. Al-Monitor was told that the incident would be reported to the Liwa Karbala PMU.

A source closely connected to local armed forces also told Al-Monitor that a former imam who had taken up arms in the fight against IS and who now leads a local PMU unit had been injured the previous day by individuals from the “southern PMU” during a dispute. Al-Monitor could not independently verify this information.

Rumors about various alleged abuses by nonlocal PMU are rife, but the area has long seen collaboration with them as essential, and many local men fight within the ranks of nonlocal ones, such as the Badr Organization.

The area is also near a political fault line between the central government and the Kurdish Regional Government (KRG) territories.

The Hamrin Mountain chain, which runs from near the Iranian border in Diyala province to northern Salahuddin and southern Kirkuk, has long been claimed by Kurdish ideologues and leaders as the ideal boundary for any future Kurdish state.

The taking back of oil-rich Kirkuk by the central government in mid-October after the Sept. 25 independence referendum called by the KRG’s then-President Massoud Barzani has, however, made any Kurdish state unlikely for the near future.

Wadis, small caves and other physical features of the Hamrin Mountains make it an ideal hiding place. It was where civilians escaped to from Hawija while the town was under IS control for three years. Many civilians died from the numerous IEDs planted on the routes or from hardship along the way.

Until the retaking of Hawija from IS control in early October, the town of al-Alam on the other side of the Hamrin Mountains had been filled with internally displaced persons from Hawija and surrounding villages.

On several visits to al-Alam over the course of about a year, Al-Monitor met with people who had made the dangerous journey at night through the mountains and heard stories of corpses seen along the route.

When Al-Monitor visited the town again in late December, most of the internally displaced persons were said to have returned to Hawija and the surrounding area. Attacks continue to occur in the area, however. Officers involved in the operation told Al-Monitor that the clearing of the Hamrin Mountains is expected to sharply reduce possibilities for insurgents to conduct such attacks.