US service member killed in Afghanistan during mission targeting ISIS affiliate

A roadside bomb killed a U.S. service member on foot patrol Tuesday in eastern Afghanistan as part of a mission to fight a growing Islamic State affiliate, the U.S.-led coalition announced.

The blast unfolded in Nangarhar Province, where American and Afghan forces have been fighting ISIS-linked militants in recent months. The offshoot group, which has as many as 1,300 members, has been recruiting former Pakistani Taliban members with the allure of higher pay, U.S. officials told Stars and Stripes.

Pentagon Press Secretary Peter Cook said the service member died in a "combat situation," but refused to call it combat when asked by Fox News.

Cook later said the service member was receiving combat pay and would likely receive combat decorations for his actions, but that determination had not yet been made. An investigation into the incident is ongoing.

"On behalf of all of U.S. Forces - Afghanistan, we are heartbroken by this loss and we extend our deepest sympathies to the families and friends of the service member," General John W. Nicholson, commander of USFOR-A, said in a statement. "Despite this tragic event, we remain committed to defeating the terrorists of the Islamic State, Khorasan Province and helping our Afghan partners defend their nation."

The U.S. is withholding the identity of the service member pending next-of-kin notification. Cook said no other U.S. service members or Afghans were hurt.

The U.S.-led coalition has killed an estimated 300 ISIS fighters in eastern Afghanistan this summer, including the group’s leader, Hafiz Saeed Khan, and several other top-ranking commanders, Stars and Stripes reports.

But the counterterrorism mission in Afghanistan that began in January 2015 has claimed the lives of 12 American service members, while another 12 have been killed in non-combat incidents, according to Pentagon data.

Fox News' Lucas Tomlinson contributed to this report.