The U.S. Army says three of its soldiers have been killed in a roadside bombing near the central Afghan city of Ghazni.
The Taliban claimed responsibility for the attack, which brings the number of U.S. soldiers to have died in the country this year to 12.
Three other U.S. soldiers were wounded when an improvised explosive device detonated on November 27, the military said.
One U.S. contractor was also wounded in the blast.
There were no further details on the identities of the soldiers or the location of the explosive device.
Taliban militants have an active presence in several parts of Ghazni Province.
The provincial capital, also named Ghazni, was overrun by the militants earlier this year before being driven off by Afghan and U.S. forces following days of heavy fighting.
The casualties came after another U.S. soldier was killed in the southwestern province of Nimroz on November 24.
A NATO statement on November 27 said an initial review showed that the soldier in Nimroz was "likely accidentally shot by our Afghan partner force," adding that the "tragic" incident occurred as they engaged in a battle with Al-Qaeda militants.
The soldier's death follows a spate of so-called "insider attacks" that have rattled foreign troops tasked with training and assisting Afghan security forces.
Some 14,000 U.S. soldiers are currently serving in Afghanistan, where the United States and NATO formally concluded their combat mission in 2014.
Most of the remaining Western forces mainly train and advise the Afghan security forces, which have been struggling against attacks from a resurgent Taliban and other militant extremist groups. There are also several thousand U.S. Special Forces conducting counterterrorism missions.
Afghan President Ashraf Ghani said earlier in November that 58 Americans had been killed in the country since the start of 2015, when Afghan troops took over primary responsibility for security.
During the same period, nearly 29,000 Afghan police and soldiers had been killed, Ghani said.
Washington is trying to reach a peace settlement with the Taliban to end the 17-year war.
U.S. envoy Zalmay Khalilzad is spearheading efforts to strike a peace deal with the Taliban before Afghanistan's presidential election, scheduled for April next year.