Two U.S. service members were killed while conducting an operation in Afghanistan on March 22, according to a statement from NATO'S Resolute Support mission.
The names of the deceased are being withheld until 24 hours after next of kin are notified.
The statement did not say where the operation was conducted.
The deaths are the third and fourth for the U.S. military in Afghanistan this year. In January, Army Ranger Sgt. Cameron Meddock, 26, and Green Beret Sgt. 1st Class Joshua "Zach" Beale, 32, died in separate incidents.
The U.S. war in Afghanistan is now in its 18th year. Some 14,000 American troops are deployed there and are charged with counterterrorism operations against al-Qaida and Islamic State fighters and with training and advising Afghan security forces in their fight with the Taliban insurgency.
More than 2,400 U.S. military personnel have been killed and more than 20,000 have been wounded since the beginning of the Afghan War in October 2001.