By Paul LeBlanc, CNN

The Pentagon identified a US Marine killed in Iraq this weekend as Gunnery Sgt. Scott A. Koppenhafer.

Koppenhafer, 35, of Mancos, Colorado, was killed Saturday by enemy small arms fire while conducting combat operations, the Department of Defense said in a Sunday news release.

He was assigned to the 2nd Marine Raider Battalion, Marine Forces Special Operations Command based at Camp Lejeune, North Carolina. The incident is under investigation, the Pentagon said.

Koppenhafer was killed while advising and accompanying Iraqi Security Forces on a planned operation in Nineveh province, Iraq, according to a press release from Combined Joint Task Force - Operation Inherent Resolve.

According to Marine Corps Times, Koppenhafer was named "Marine Special Operator of the Year" in 2018 by the Marine Corps Association for his role in guiding elite Iraqi Special Operations Forces in northern Iraq.

Koppenhafer was supporting Operation Inherent Resolve, the official name for the US-led operation fighting ISIS. A Pentagon inspector general's report on the fight against ISIS released earlier this month warned that "despite losing its territorial 'caliphate,' the Islamic State in Iraq and Syria (ISIS) solidified its insurgent capabilities in Iraq and was re-surging in Syria."

Koppenhafer joined the Marine Corps in 2005 and spent the last 10 years as a critical skills operator with the Marine Forces Special Operations Command. He had multiple deployments with the 2nd Marine Raider Battalion and his decorations include two Bronze Stars. He is survived by his wife and two children.