The soldier died on Saturday in Afghanistan's northern Faryab province "as a result of injuries sustained from enemy small arms fire during combat operations," said the U.S. Defense Department in a statement.
The soldier was supporting Operation Freedom's Sentinel in Afghanistan, the statement added.
The Pentagon said that the incident is currently under investigation.
The United States maintains some 14,000 troops in Afghanistan, largely providing training missions to local Afghan forces while also conducting counterterrorism operations against terror groups.