The service member is the 17th American killed in combat in Afghanistan this year -- the highest number since the end of 2014.
"In accordance with U.S. Department of Defense policy, the name of the service member is being withheld until 24 hours after family notification is complete," Resolute Support, the NATO-led mission in Afghanistan, said in a statement on Monday.
Last week, the president declared that peace talks between the U.S. and the Taliban were officially dead, after calling off a secret meeting with its leaders at Camp David.
For months, the U.S. had been negotiating a peace deal that would potentially bring an end to the 18-year war in Afghanistan, the longest war in American history. However, a car bomb -- claimed by the Taliban -- that killed an American soldier in Kabul last week caused the president to cancel the talks.
"They thought they had to kill people in order to put themselves in a little better negotiating position," Trump told reporters on the White House south lawn last week. "When I heard, very simply, that they killed one of our soldiers and 12 other innocent people, I said, 'There is no way I'm meeting on that basis. There is no way I’m meeting.'"
The American killed in that attack was Sgt. 1st Class Elis Angel Barreto Ortiz of Morovis, Puerto Rico, who served with the 3rd Combat Brigade, 82nd Airborne Division.
Despite the failed talks, the president may decide to withdraw some forces without a peace deal, bringing the total number of U.S. troops in Afghanistan down from approximately 14,000 to 8,600, according to U.S. officials.
Meanwhile, the chief U.S. negotiator for the talks, Ambassador Zalmay Khalilzad, is back in Washington, after months of meetings with the Taliban in Qatar and with Afghan officials in Kabul.
State Department spokesperson Morgan Ortagus said last week that the U.S. still hopes to achieve peace in Afghanistan and bring American troops home but acknowledged that, "how we get there obviously is going to diverge from how we thought we were going to get there two weeks ago."