Defense Secretary Ash Carter said the service member's death was a "reminder that our people... are in harm's way."
UPDATE, 21 October 2016, 2:30 PM EST:
The Defense Department has identified the troop killed in Iraq Thursday as Chief Petty Officer Jason C. Finan, 34, of Anaheim, California. He died of wounds sustained in an improvised explosive device blast. He was assigned to Explosive Ordnance Disposal Mobile Unit Three.
WASHINGTON – A United States service member was killed in Northern Iraq by a roadside bomb Thursday as he assisted local forces in their push to retake Mosul from ISIS, marking the first U.S. combat casualty in the effort.
Defense Secretary Ash Carter said the service member’s death was a “reminder that our people who are participating in the counter-[ISIS] campaign, whether they be flying aircraft or working with the Iraqi security forces and the other forces and enabling their consistent advances of the kind that we see in the region of Mosul today, are in harm’s way.”
“It’s necessary for us to enable in this case the Iraqi security forces and the peshmerga in northern Iraq — and it appears that it was in that role that the service member was killed,” Carter added.
More than 100 U.S. special operations troops are operating with Iraqi forces as “enablers,” and hundreds more are participating in the Mosul campaign in a supporting role in bases back further from the frontline.
He was the fourth U.S. combat death in Iraq since the U.S. began military operations against ISIS with airstrikes in August 2014.
In September, the Pentagon announced that 615 more troops would deploy to Iraq for the Mosul fight, raising the U.S. troop cap to 5,262 soldiers. There are more U.S. forces in Iraq now than at any time since the 2011 U.S. withdrawal.
ISIS took control of Mosul in June 2014, and from a city mosque ISIS leader Abu Bakr al Baghdadi proclaimed the creation of a caliphate.
The U.S. commander overseeing the Middle East, General Joseph Votel, said Wednesday that the campaign is “on track” to take control of the city from about 5,000 ISIS fighters in and around it.