A U.S. service member was killed and another wounded Monday in an apparent insider attack in eastern Afghanistan, officials said.

The name of the fallen service member will not be released until family members are notified. The wounded service member is in stable condition, according to officials from the Resolute Support mission in Afghanistan.

“The sacrifice of our service member, who volunteered for a mission to Afghanistan to protect his country, is a tragic loss for all who knew and all who will now never know him,” said Army Gen. Scott Miller, who just on Sunday took command of Resolute Support and U.S. Forces–Afghanistan. “Our duty now is to honor him, care for his family and continue our mission.”

The U.S. service member killed Monday is the sixth American killed in Afghanistan this year.

His death comes less than one month after Sgt. 1st Class Reymund Transfiguracion, a Special Forces soldier with 3rd Battalion, 1st Special Forces Group, died from wounds suffered in an improvised explosive device attack in Afghanistan’s Helmand province.

And it comes as Afghan forces are struggling to contain a resurgent Taliban and an increasingly powerful Islamic State affiliate. The Taliban control several districts across Afghanistan, and both groups have launched a relentless wave of attacks in recent months.

“The world recognizes Afghanistan cannot be a safe haven for terrorism, the world recognizes that we cannot fail. I know this has been a long fight, and it has been generations for us, for the Afghan people,” said Miller, who most recently led the Joint Special Operations Command, during the change of command ceremony Sunday in Kabul.

The Associated Press contributed to this report.