An Army Special Forces soldier was killed while conducting counterterrorism operations in Afghanistan late Saturday, US forces in Afghanistan have announced in a release.

The soldier was mortally wounded while helping Afghan forces conduct operations against Khorasan, the local branch of the Islamic State of Iraq and Syria, Navy Capt. Bill Salvin, a spokesman for the NATO-led coalition in Afghanistan, told CNN.

The commander of US forces in Afghanistan, Gen. John W. Nicholson, offered “deepest condolences to the family and friends of our fallen comrade” on behalf of all US forces there. “We will always remember our fallen comrades and commit ourselves to deliver on their sacrifice.”

US troops regularly perform counterterrorism operations against the ISIS affiliate, which has a presence in Nangarhar Province, where the soldier was killed. Those operations are sometimes carried out in conjunction with Afghan forces.

The US counterterrorism mission is separate from the NATO-led effort to train, advise and assist the Afghan army and police force.

There are about 8,400 US troops in Afghanistan. This is the first US combat death in Afghanistan in 2017. The number of US casualties in Afghanistan has fallen sharply since the end of US-led combat operations in 2014.