BARTELLA, Iraq (AP) — In a significant intensification of the battle for Mosul, elite Iraqi special forces joined the fight Thursday, unleashing a predawn assault on an Islamic State-held town east of the besieged city. The U.S. military announced the first American death since the operation began.

Central Command said the U.S. soldier died Thursday from wounds sustained in a roadside bomb explosion in northern Iraq, but did not say if the soldier was part of the Mosul campaign. More than 100 U.S. special operations forces are embedded with Iraqi units in the offensive, and hundreds more are playing a support role in staging bases.

As Iraq’s special forces advanced on the town of Bartella, nine miles (15 kilometers) from Mosul’s outskirts, they faced a familiar foe – trucks packed with explosives and driven by suicide bombers.

The militants’ signature battlefield tactic, the weapons offered a glimpse at what Iraqi forces can expect as they approach the extremists’ biggest urban bastion.

The pre-dawn assault was part of a multi-pronged operation on eastern approaches to Mosul, Iraq’s second-largest city. Attack helicopters strafed militant positions as they advanced amid a hail of gunfire.

The U.S.-trained special forces , officially known as the Counter Terrorism Service, are widely seen as Iraq’s most professional and least sectarian fighters, and have served as the shock troops in previous campaigns against IS. They are expected to lead the charge into Mosul.

IS militants unleashed at least nine suicide car and truck bombs against the advancing troops, eight of which were destroyed before reaching their targets, while the ninth struck an armored Humvee, Lt. Col Muntadhar al-Shimmari told The Associated Press.

He did not give a casualty figure, but another officer said five Iraqi soldiers were wounded. The officer spoke on condition of anonymity because he was not authorized to release information.

“After we break them in Bartella, everywhere else, they will crumble,” said Maj. Gen. Fadhil Barwari. He said IS had few defenses in the town, which was almost completely empty of civilians. “They just left some snipers and suicide car bombs,” he said.

Meanwhile, Iraqi Kurdish forces, known as peshmerga, announced a simultaneous attack, with peshmerga fighters deployed on mountains northeast of Mosul descending from their positions and charging toward the front line.

Under cover of mortar and gunfire, the Kurdish troops used bulldozers and other heavy equipment to fill trenches dug by the militants as part of their defense of the IS-held village of Barima, then advanced with armored vehicles toward the extremists’ positions.

Military operations also appeared to be underway in the town of Bashiqa, northeast of Mosul, where thick smoke could be seen billowing up. A day earlier, Bashiqa was pounded by airstrikes and mortar fire from peshmerga positions high above.

Lt. Gen. Talib Shaghati told a news conference late Thursday that the special forces had succeeded in retaking Bartella. But Iraqi forces were still facing stiff resistance inside the town shortly before he spoke, and past advances against IS elsewhere in Iraq have often proved fleeting.