PENTAGON - The Pentagon says Islamic State fighters were responsible for attack in southwestern Niger that killed four American soldiers, as new details suggest local villagers may have played a role in the ambush.

Pentagon spokeswoman Army Lt. Col. Michelle Baldanza told VOA Wednesday that Islamic State fighters ambushed U.S. and Nigerian forces during the Oct. 4 fire fight, which also killed four of Niger's security forces.

American special forces troops, known as Green Berets, had just completed a meeting with local leaders and were walking back to their vehicles when they were attacked, according to a U.S. official, who spoke to VOA on the condition of anonymity since the investigation is still ongoing.

The soldiers said the meeting ran late, and some suspected that the villagers were intentionally delaying their departure, the official said.

Niger's defense ministry has confirmed the fire fight occurred near the village of Tongo Tongo in the Tillaberi region. Eight other Niger troops were wounded in the attack, and two American troops were wounded and airlifted to Germany for medical treatment.

Strategic ally

Niger is a key U.S. ally in the fight against terrorism and is situated in a dangerous region of the Sahel plagued by multiple extremist groups and traffickers, said Lisa Mueller, an assistant professor of political science at Macalester College and expert on politics in the area.

During Barack Obama's presidency, the U.S. built drone bases in Niger's capital, Niamey, and in the northern town of Agadez. The U.S. has about 800 service members in Niger to provide support for the U.S. embassy and counter-terrorism training for government forces battling Islamist militant groups.

"The United States has provided support for the military of Niger, especially in the way of training forces to combat multiple terrorist groups that have encroached into Niger from several of the country's borders," Mueller said.

Niger faces threats from Nigeria-based Boko Haram along its southern border and Algeria-based al-Qaeda in the Islamic Maghreb along its porous borders to the west and north. Pockets of Islamic State fighters operate in the west.

"Really, from almost all sides, Niger is facing attacks from armed extremist groups. And, because the government of Niger has been a strong ally to the counterterrorism efforts, it's been natural for the United States to station its counterterrorism forces in that country," Mueller said.

Caught off guard

U.S. officials said they have information about the group that conducted the attack in Tongo Tongo but declined to release details.

"We are resolved and stalwart in our efforts to go after those who attacked us," U.S. Africa Command Spokesman Army Col. Mark Cheadle said in a conference call on Friday.

The Pentagon also said it is reevaluating its force protection measures in the region.

Mueller, who has traveled and conducted research in Niger, said radicalism in the country is mostly imported from surrounding countries, but that could change.

"Islam in Niger has, for generations, been very tolerant, been very resistant to radicalization, especially compared with societies elsewhere in the Sahel," she said.

"It's not guaranteed that that won't change, and there are some hints that especially youth in certain regions of Niger are more receptive to radical recruitment. But it's not the overwhelming trend as of now, and so I just want to underline that terrorism in Niger is largely a matter of foreign policy and not of domestic concerns."