"On Oct. 20, 2016, a U.S. service member died from wounds sustained in an improvised explosive device blast in northern Iraq. Further information will be released as appropriate," according to a statement issued by the U.S.-led coalition in Iraq. "It is CJTF-OIR policy to defer casualty identification procedures to the relevant national authorities."
U.S. officials said the American service member was riding in an armored vehicle with Iraqi special forces when the roadside bomb went off just north of Mosul. The wounded individual was sent to Erbil for treatment and died from his injuries. No one else was hurt in the blast.
The identity of the deceased individual will be released after family members are notified, officials said.
Today marked the fourth day of the operation to liberate Mosul, Iraq’s second-largest city, from the Islamic State group's control. The death of this American service member represents the first U.S. casualty in the region since the operation began.
About 18,000 Iraqi forces, 10,000 Kurdish forces known as peshmerga and a few thousand Iraqi federal police launched the massive military offensive on Monday. Roughly 100 American advisers are also involved in the mission, which is divided into two fronts -- one west of the Great Zab River and the other just north of Qayyarah.
Defense officials have said the fight for Mosul could be long and the American role is critical as they assist Iraqi and Kurdish forces in the region.
Only a "small number" of the nearly 5,000 American troops stationed in Iraq could find themselves in what a Pentagon spokesman called "a combat environment" while they advise the Iraqi and Kurdish forces involved in the operation.
"Early indications are that Iraqi forces have met their objectives so far and that they are ahead of schedule for this first day,” said Pentagon spokesman Peter Cook at a briefing Monday. “This is going according to the Iraqi plan, but again, it's early and the enemy gets a vote here. We will see whether ISIL stands and fights."
Iraqi Prime Minister Haider al-Abadi said the operation is advancing “more quickly” than expected, as an Iraqi-led coalition of forces captured several more villages around Mosul today.
According to Kurdish peshmerga commanders, their forces have so far taken the towns of Barima, North Smaqa, South Smaqa, Fazilya, Nawaran, Imam Razil and the village of Dere. The troops are working to clear booby traps and IEDs from all the settlements under ISIS rule.
The peshmerga commanders told ABC News that this morning’s operation aimed to clear more of the outlying villages around Mosul and to tighten the noose around the Islamic State's last major stronghold in Iraq.
Meanwhile, to the south of Mosul, the Iraqi army is carefully pushing forward today while encountering booby-trapped explosives and fierce resistance from ISIS militants in some villages on the city's outskirts.
Iraqi special forces joined the fight for Mosul this morning. Iraqi Army Maj. Gen. Maan al-Saadi said the elite troops, also known as counterterrorism forces, advanced on the town of Bartella with the aid of U.S.-led coalition airstrikes and heavy artillery. The special forces are expected to carefully lead the way into Mosul.
"God willing, we will take this town today," he said of Bartella, which ISIS seized in 2014.
Sarah Kolinovsky, Matt McGary and Chad Murray contributed to this report.