Pentagon officials said they would also examine how many training missions in border areas like this the Special Forces had conducted before Wednesday’s assault, and whether the Americans inadvertently settled into a pattern of predictable activities that Qaeda fighters could exploit with deadly consequences.
The concerns are particularly acute given that the ambush took place near the village of Tongo Tongo, just inside Niger in a region recently destabilized by cross-border jihadist attacks on the Nigerien army and refugee camps. In mid-June, the Nigerien army mounted an operation in this same northern Tillaberi region to take on the jihadists.
In a statement on Thursday morning, the Pentagon’s Africa Command said the Americans were providing “advice and assistance to Nigerien security force counterterror operations” when they came under fire. Two other American troops, members of the 3rd Special Forces Group, were also wounded and a Nigerien soldier was killed.
“Our country has just been attacked once more by terrorist groups, an assault which sadly has resulted in a large number of casualties,” President Mahamadou Issoufou of Niger said at a regional meeting on Thursday in Niamey.
The firefight lasted roughly 30 minutes and involved less than a dozen United States troops and more than 20 Nigerian soldiers. The official said they ran into a large group of militants traveling in pick-up trucks mounted with machine guns, known as technicals, that took them by surprise. United States drones were in the area, but it is unclear how close they were at the time of the attack given the mission’s perceived low risk.
French attack helicopters responded to calls for help but it is unknown if they fired on the militants or only made a show of force. The wounded were evacuated to the capital of Niamey and the wounded Americans were then put on a plane to Germany where they were receiving medical treatment.
The military has not yet released the names of the American soldiers killed, pending notification of their families.
While no group has claimed responsibility for the attack, officials believe that Al Qaeda in the Islamic Maghreb was involved. The extremist group, pushed from its territory in northern Mali after the French military intervened in 2012, has been increasingly active in recent years. Since 2016 the group has staged a number of attacks across the broader Sahel, a stretch of territory that runs from Senegal to Sudan, and routinely ambushes United Nations peacekeepers in the region.
While the United States provides limited support to the French troops in Mali, namely sharing drone feeds and other intelligence, it has invested a significant amount of resources to the south in Niger, where about 800 American troops are stationed.
Since 2013, unmanned American aircraft have launched from a clandestine airfield in Niamey. Americans are also helping construct a $50 million drone base for French and American aircraft in Agadez. When completed next year, it will allow Reaper surveillance drones to fly from hundreds of miles closer to southern Libya, to monitor Islamic State insurgents flowing south and other extremists flowing north from the Sahel region.
More than two dozen Army Special Forces — like those attacked on Wednesday — train the Nigerien military and help with intelligence gathering for the local forces.
The deaths of three Americans in the country highlight the inherent risk associated with conducting even noncombat missions in a region beset with violence and a growing assortment of militant groups. In May, a member of the Navy SEALs was killed and two other American troops were wounded during a raid in Somalia, the first American combat fatality there since 1993.
“The clash demonstrates the seriousness of the militant threat in the region,” Michael R. Shurkin, a senior political scientist at RAND and former C.I.A. analyst, said of Wednesday’s ambush. “Since Trump took office, U.S. policy in the region has been more or less adrift. This could force someone finally to take the tiller by the hand.”