Photographer John Moore witnesses life at the edge of the front lines in the fight against ISIL

A peshmerga fighter next to a destroyed building in the town.

Officials say that much remains to secure the town, which, they fear, has been laid with mines and booby traps. Bram Janssen / AP

The operation was assisted by airstrikes from U.S.-led forces. Ari Jalal / Reuters

Members of Kurdish peshmerga forces walk in the town of Sinjar, Iraq, Nov. 13, 2015, after an offensive to retake the town from ISIL. Ari Jalal / Reuters

Peshmerga forces raised a Kurdish flag in the center of Sinjar on Friday, having seemingly pushed out ISIL fighters from the strategically important northern Iraqi town.

It follows a major offensive to retake the town, assisted by U.S. airstrikes and American ground troops in an advisory role, the Pentagon said. Sinjar was seized by the Islamic State in Iraq and the Levant (ISIL) last year in a push that resulted in tens of thousands of Yazidis fleeing.

Speaking Friday, Massud Barzani, the president of the Iraqi Kurdish region, announced the town's "liberation."

"Without doubt, any victory in any area will have a big impact on achieving victory in the remaining areas. And without doubt the liberation of Sinjar will have a big impact on liberating Mosul too," he added, referring to the key city that U.S. and Iraqi officials are targeting in the pushback against ISIL.

Earlier, peshmerga Maj. Ghazi Ali, who oversees one of the units involved in the mission, dubbed Operation Free Sinjar, said thousands of Kurdish fighters entered the town from three directions Friday morning.

They encountered minimal resistance during Friday's push, he said. He described the situation in the city as still dangerous, however, and warned that it was too soon to declare victory.

Iraq's highest Shia religious authority, Ayatollah Ali al-Sistani, praised peshmerga fighters in his Friday sermon for their efforts to capture Sinjar from ISIL.

Col. Steven Warren, a spokesman for the U.S.-led coalition, confirmed only that peshmerga fighters raised their flag on grain silos in the eastern part of the town. He said they had not fully retaken Sinjar.

There is reason for caution. An earlier attempt to wrest back control of the town from ISIL — at the foot of Mount Sinjar, about 30 miles from the border with Syria — stalled in December. Since then, ISIL has been reinforcing its ranks.

But this week’s offensive that could provide critical momentum in efforts to defeat ISIL, and the new mission in Sinjar has cut off the ISIL's supply lines between its strongholds of Mosul in Iraq and Raqqa in Syria.

ISIL fighters overran the area of Sinjar in August last year. During the onslaught, the group launched a wave of attacks against the minority Yazidi community — members of an ancient religion whom ISIL views as heretics and accuses of worshiping the devil.

The Yazidis fled into the mountains, where ISIL fighters surrounded them, trapping and exposing them to the blazing heat. Many others were held captive.

The crisis prompted the U.S. to launch aid airdrops, and in August 2014, it initiated airstrikes in what would mark the beginning of a broader coalition effort to battle the group in Iraq and Syria.

Various Kurdish militias on the town's edge have been fighting guerrilla battles for months against ISIL fighters in Sinjar.

The factions include the Turkey-based Kurdistan Workers' Party, the Syria-based People's Protection Units (better known as the YPG) and Yazidi-led forces calling themselves the Sinjar Resistance.

Peshmerga fighters also hold positions farther outside the town.

Diar Namo, a 26-year-old deputy commander of a peshmerga unit stationed there, said the skies above Sinjar were largely quiet overnight after intense coalition airstrikes on Thursday. From his frontline observation post, he said he saw little movement inside the city before Kurdish forces moved in Friday.

“We saw more than 50 Daesh [fighters] flee overnight,” he said, using an Arabic acronym for ISIL. “Before, there were only 200 to 300 in the city.”

Officials with the U.S.-led coalition estimated there were 400 to 550 ISIL fighters in Sinjar before the offensive began Thursday.

Southeast of Sinjar, in the village of Soulag, four peshmerga fighters were killed when a homemade bomb targeting their truck exploded, according to fighters in their unit.

Homemade roadside bombs and explosive-laden cars targeting peshmerga convoys significantly slowed Thursday's advance through Sinjar's eastern and western fringe.

Al Jazeera and wire services