Two American soldiers were killed in the attack on the convoy near the airport in the southern Afghan city of Kandahar, the Pentagon said.
Two US soldiers were killed in Afghanistan's restive southern province of Kandahar on Wednesday when a Taliban suicide bomber rammed a vehicle filled with explosives into a convoy of foreign forces.
"Two US service members were killed in action in Kandahar, Afghanistan, when their convoy came under attack," Pentagon spokesman Navy Captain Jeff Davis said.
"US Forces Afghanistan will provide additional information as it becomes available," he added.
TRT World's Arabella Munro has this report.
The assault is the latest blow to NATO forces, who ended their more than a decade-long combat mission in Afghanistan at the end of 2014.
Since then Afghan troops and police, beset by soaring casualties, have struggled to beat back the resurgent Taliban, while facing the growing presence of Daesh.
Afghan officials said the attack, which was quickly claimed by the Taliban, happened around noon (0730 GMT) in the Daman area of Kandahar.
NATO confirmed in a statement that a convoy was attacked and did "cause casualties" but did not immediately give further details.
At least one witness reported seeing three bodies pulled from one of the vehicles.
The Taliban have a heavy presence in poppy-growing Kandahar province and have launched repeated attacks there.
They have been ramping up their campaign against beleaguered government forces, underscoring rising insecurity in the war-torn country during the summer fighting season, when the warmer weather tends to spur an increase in militant attacks.
US troop increase?
The attacks come as United States President Donald Trump weighs sending more American troops to Afghanistan nearly 16 years after the US invasion to topple the Taliban regime.
US troops in Afghanistan now number about 8,400, and there are another 5,000 from NATO allies, a far cry from the US presence of more than 100,000 six years ago. They mainly serve as trainers and advisers.
American military commanders in Afghanistan have requested thousands of extra boots on the ground and Defense Secretary Jim Mattis is believed to be close to presenting a new US military strategy for Afghanistan to Trump.
Tuesday's attack came a day after suicide bombers throwing grenades killed more than 30 worshippers at a mosque in Afghanistan's main western city of Herat.