Green Berets clear rooms inside a compound during a training mission held Feb. 20, 2015, at Eglin Air Force Base in Northwest Florida. (Photo by Capt. Thomas Cieslak/ U.S. Army)

The Pentagon has identified the U.S. Army Green Beret who was killed Wednesday battling Islamic State militants in eastern Afghanistan.

Staff Sgt. Aaron R. Butler, 27, of Monticello, Utah was killed by an improvised explosive device in Nangahar Province, the Pentagon said in a statement late Thursday. An unknown number of U.S. troops were also injured during the fighting as were several Afghan troops working alongside their American counterparts.

Butler belonged to a Special Forces team from 19th Special Force Group and was based out of Camp Williams Utah. The 19th Group is an Army National Guard unit with detachments all over the United States, including Washington and Colorado. A Green Beret from 19th Group, Staff Sgt. Matthew McClintock, was the first U.S. combat death in Afghanistan for the year 2016.

Butler’s death brings the total of Americans killed by hostile fire in Afghanistan this year to 10. Seven of those deaths were directly related to fighting Islamic State militants in the eastern part of the country.

The U.S. military has invested considerable resources and troops in battling the Islamic State’s Afghan affiliate. Yet despite numerous offensive operations and a concerted bombing campaign that involved the use of a 22,000-pound bomb and several surgical strikes against the group’s leaders, about 1,000 of the militants have remained dug in along the Pakistani border, according to U.S. military officials in Kabul.

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