Staff Sgt. Matthew McClintock, 30, died from wounds suffered when the enemy attacked his unit with small arms fire, according to the DoD announcement released late Wednesday.
The incident is under investigation.
McClintock, of Albuquerque, New Mexico, was assigned to 1st Battalion, 19th Special Forces Group, in Buckley, Washington.
McClintock and his fellow Green Berets, from 1st Battalion's A Company, deployed to Afghanistan in July, according to information from the Washington Army National Guard.
McClintock joined the Army in 2006. After completing his training, McClintock was assigned to the 1st Cavalry Division, deploying to Iraq in 2007.
He was chosen for selection in the U.S. Army Special Forces School in May 2009, according to information from the Guard. He was assigned to 1st Special Forces Group, at Joint Base Lewis-McChord, Washington, in November 2010.
He deployed to Afghanistan from August 2012 to May 2013.
"Staff Sergeant McClintock was one of the best of the best," said Maj. Gen. Bret Daugherty, commander of the Washington Guard, in a statement. "He was a Green Beret who sacrificed time away from his loved ones to train for and carry out these dangerous missions. This is a tough loss for our organization."
McClintock was killed and two others were wounded in hours-long fighting Tuesday near the city of Marjah, in southern Helmand province.
The troops' evacuation was delayed Tuesday when one helicopter took fire and was unable to land, and another was unable to take off.
Lawhorn told the AP that U.S. special operations forces were advising their Afghan counterparts during the battle. The Taliban have recently attacked a number of cities in Helmand, one of several fronts where the insurgents have advanced in the year since the U.S. and NATO formally concluded their combat mission.
Initial reports about the battle were sketchy.
"There is still a fight going on," Pentagon press secretary Peter Cook said Tuesday afternoon, hours after the casualties were sustained. "We don't yet have all the details surrounding what has taken place."
Cook added two U.S. helicopters were dispatched to the scene to provide medical evacuation for the U.S. casualties but could not complete the mission, according to the AP. One was waved off after taking fire and returned safely to its base, Cook said. The other, an Air Force HH-60 Pave Hawk, landed safely but was unable to take off because its rotor struck a wall.
Michelle Tan is the editor of Army Times and Air Force Times. She has covered the military for Military Times since 2005, and has embedded with U.S. troops in Iraq, Afghanistan, Kuwait, Haiti, Gabon and the Horn of Africa.