SINJAR, Iraq: The ousting of ISIS forces from the Iraqi town of Sinjar is being touted by Kurdish leaders as a major military victory. But commanders on the ground say the extremists largely withdrew, fleeing during a pause in airstrikes.

The capture of Sinjar by U.S.-backed Kurdish fighters last week did mark a significant gain against the extremists, cutting off a main supply route between ISIS territories in Iraq and Syria.

The fighters’ apparent escape suggests the Kurds’ priority was to seize the town – both for its strategic and symbolic value – not trap and crush the ISIS forces in it outright. ISIS’ tactical retreat also points to the pragmatism that the group can show when badly outgunned – a contrast to other cases when its militants fight to the death, usually during offensives when they aim to wreak as much damage as possible before being killed.

Over the weekend, Kurdish fighters walked casualty through the streets of Sinjar, a once-sleepy town at the foot of a mountain in the deserts near Iraq’s border with Syria. Streets were filled with rubble of collapsed homes, twisted metal and burned-out cars; but this was the destruction wreaked by clashes and airstrikes over more than a year since ISIS militants swept in and took over.

Though preceded by heavy U.S. airstrikes, the actual capture of the town Friday saw little fighting. While Kurdish officials claimed that hundreds of ISIS fighters were killed, no bodies were immediately uncovered Friday. As troops advanced through the town on foot, the only sound that could be heard was that of celebratory gunfire.

Farhan Eado – a Sinjar native from the Yazidi religious minority who is a sergeant in the Iraqi Kurdish militia forces known as the peshmerga – said he wasn’t surprised by the sudden calm. Late into the night Thursday and early Friday, he said he watched dozens of ISIS fighters stream out of the town, from his position on a foothill of Sinjar Mountain with a clear view of the town below.

“They all fled once the airstrikes stopped last night,” he said, referring to a pause in the heavy campaign of U.S.-led coalition airstrikes during the first day of fighting. “They were leaving in every way they could, by car, some even walking.”

The Pentagon reported that during the first day of the offensive coalition planes conducted more than 30 airstrikes on Sinjar and surrounding areas. From 400-600 ISIS fighters were estimated to be in Sinjar before the assault. Col. Steven Warren, the spokesman for the U.S.-led coalition in Baghdad said an estimated 200 were killed in airstrikes, and several hundred more were believed killed by the Kurds.

“We had not seen large numbers of ISIL attempting to escape,” Warren said, using an alternative acronym for ISIS. “If we had, we would have struck.”

But before the Kurdish forces moved in Thursday, the commander of a unit at a northern artillery position, Capt. Ramazan Sanaan, said the operation was intentionally leaving an escape route for ISIS fighters to avoid an urban battle that could bring heavy casualties. A key road connecting Sinjar to smaller villages to the south was left open, he said.

“We want to give them that option to run away from us,” he said. He spoke to AP as his unit sipped tea and posed for mobile phone photos on the town’s outskirts. “We are waiting for Sinjar to be completely clear [of ISIS fighters].”

Seizing Sinjar had strong symbolic value and the president of Iraq’s autonomous Kurdish region, Massoud Barzani, quickly sought to reap the political benefits with a carefully orchestrated press conference Friday. With the town visible behind him, he claimed Iraqi peshmerga forces were the only ones involved in the fighting.

But other Kurdish groups were clearly visible in the operation. Just hours before the press conference Syrian Kurdish fighters known as the YPG could be seen moving back and forth across the frontline. Speaking to an Associated Press team inside Sinjar, YPG fighters said they had been on the ground for days clearing ISIS positions. Eado, with the Iraqi peshmerga, confirmed small YPG units were carrying out ground operations and retaking territory inside Sinjar proper while peshmerga forces massed behind fortified frontline positions.

A tactical retreat by ISIS would not be unprecedented. Over the summer, ISIS fighters suddenly melted away from the Syrian town of Tal Abyad once the tide turned against them in heavy clashes with Kurdish forces, which then marched into the strategic town on the border with Turkey.

Analysts say that ISIS’ decision to withdraw could come down to a question of the group allocating its resources. “They can only fight on so many fronts at once,” said Aymen al-Tamimi, an expert on Syrian rebels and Islamist extremist groups and a fellow at the Middle East Forum think tank. “And in this case there are probably too many fronts.”

The same day the Kurds retook Sinjar, a U.S.-backed coalition of local fighters across the border in Syria recaptured the strategic town of Hol from the militants.

Desertions may also be a growing problem within ISIS, Tamimi said. He pointed to a document put out by ISIS last month urging its fighters who abandoned their posts to return “with the promise that no harm will come to you or evil touch you ... so that you may begin with a new page.”