Pentagon spokeswoman Dana White said a joint US Africa Command military team on November 12 discovered the remains at the site where Sergeant La David Johnson's body was recovered following the October 4 attack.

"Today, we can confirm that the Armed Forces Medical Examiner has positively identified these remains as those of Sergeant Johnson," White said in a statement, without giving any additional details.

A US defense official later told AFP that the remains were "small bone fragments."

Johnson was one of four US soldiers and five Nigerien troops killed in the ambush of a joint US-Niger patrol in the village of Tongo Tongo near the Niger-Mali border.

He was buried October 21, 2017 in Hollywood, Florida.

Johnson's patrol was attacked by about 50 local fighters associated with the Islamic State group.

Questions have been raised over why it took hours before backup support reached the patrol, and why Johnson's body was left behind and only recovered the following day.

His death was politicized when a US congresswoman accused Donald Trump of being insensitive during a phone call with Johnson's widow, an account she and her mother also supported while the president denied it.