Kurdish Peshmerga fighters

DOHUK, Iraq—A military operation by Kurdish forces against Islamic State began Thursday morning, according to a Kurdish government announcement, as thousands of fighters converged on a key town and sought to choke off a supply line to the militants.

The offensive will deploy 7,500 Peshmerga fighters to retake the town of Sinjar from Islamic State, also known as ISIS or ISIL. The operation, called “Free Sinjar,” will open three fronts to seal off the town, take control of supply routes and set up a buffer zone to protect residents from artillery, according to a statement from the Kurdish Regional Government.

The road from the Kurdish city of Dohuk to Sinjar was dotted with checkpoints on Thursday.

At a river crossing in the town of Feshkhabour, a two-hour drive from the front line, hundreds of camouflaged men carrying Kalashnikovs clamored for rides to the battle.

Peshmerga fighter Raiz Farhan, 21, was piled into the back of a flatbed truck with more than a dozen others. They got a call Wednesday night, he said, telling them their leave had been canceled and that they should get to Sinjar.

“Daesh isn’t that strong and we’ll defeat it,” he said, using an Arabic name for Islamic State.

Sinjar carries strategic as well as symbolic importance.

The town sits on an important highway Islamic State uses to ferry supplies from Raqqa, Syria to Mosul in northern Iraq. Islamic State seized the city last summer in a major offensive, widening its self-described caliphate to about an hour’s drive from the Kurdish capital, Erbil.

Kurdish and U.S.-led coalition forces are coming under pressure to show they can roll back Islamic State’s gains in Syria, as well as Iraq. Iran-backed Shiite militias have stepped up their efforts to regain territory in Iraq from Islamic State, the Sunni extremist group. But such battles have also fanned sectarian tensions and tested Iraq’s political stability.

Ahead of the attack on Tuesday, American and other coalition aircraft provided support, with six airstrikes destroying three Islamic State units and 18 staging areas, according to a statement from the Coalition Joint Task Force. On Wednesday night, the Kurdish government said coalition warplanes hit dozens of Islamic State positions to prepare for the assault.

A U.S. military official said the coalition had already supported the operation with 20 airstrikes overnight, but added that Islamic State is well-prepared to defend the area. U.S. officials estimate it will take more than two days for the Kurds to take the town, and another week before they assume full control of Sinjar.

Last August, soon after Islamic State took Mosul, militants pushed into Sinjar, forcing approximately 50,000 Yazidis to flee the town and take refuge on nearby Sinjar Mountain, according to United Nations estimates at the time. The organization estimated that some 200,000 people fled the area as refugees.

A hallmark of Islamic State campaign in Sinjar was its brutality against the Yazidi people, who follow a religion that predates Islam. Many women of the community were turned into sex slaves. Many Yazidi men were executed.

In a first step in coalition efforts to broaden action against Islamic State, U.S. and coalition forces have air dropped food and water to those trapped on the mountain and bombed Islamic State positions to blunt their military advances. A counteroffensive by Kurdish forces in December retook part of the city, although since then little progress has been made.

In the days leading up to the operation, Kurdish forces made clear they intended to attack, but delayed the start of the offensive. A Kurdish government official earlier this week in an interview blamed winter rains and bad weather on the delay but said the offensive was imminent. Kurdish President Masoud Barzani decided to go to the front lines to coordinate matters, the official said.

Infighting between Kurdish factions could also have led to the delay, with each jockeying for control over the operation. Haider Shashu, a commander allied with the Marxist Kurdistan Workers’ Party said that all Kurdish forces, including themselves, will be crucial to the operation’s success, and squabbling needs to take a back seat.

“What flag to be raised isn’t the priority now,” Mr. Shashu said. “The priority for everyone is to free the city of Sinjar.” (The Wall Street Journal)