A United States army vehicle hit an improvised explosive device as it entered a firing range during a training exercise near the town of Oullam, south-west Niger, the army says.
Its statement added: “U.S. and Nigerien partner forces were conducting a training exercise when the explosion occurred.”
The US is supporting Niger in its fight against Islamist militants in the region.
Nigerien partner forces have secured the scene and are assessing the incident.
“U.S. forces are in Niger to assist our African partners in their efforts to counter violent extremist organizations,” said Karns. “A safe, stable, secure and prosperous Africa is an enduring United States interest.”
In 2017, four US soldiers and four Nigerian soldiers were killed in an ambush near the Malian border.