An American soldier died during an operation in Afghanistan late Saturday, a U.S. military spokesman posted on Twitter.

“The soldier was mortally wounded late Saturday during an operation in Nangarhar Province,” wrote U.S. Navy Capt. Bill Salvin, a spokesman for U.S. forces in the region.

The operation was part of the NATO-led Resolute Support, a mission against ISIS-Khorasan, a branch of the Islamic State.

Nangarhar Province in the eastern border of the country with Pakistan. It is home to the militants that took on both the Taliban and Afghan government.

The circumstances of the soldier’s death were not immediately released. Salvin told Reuters the soldier was a Special Forces operator.