The Defense Department "is aware of alleged photos and IS propaganda video from the Oct. 4, 2017 terrorist attack in Niger. The release of these materials demonstrates the depravity of the enemy we are fighting," the Pentagon said in a statement.

The nine-minute video includes a compilation of still and video footage, some of it IS and some American.

The video shows what appears to be the attack itself, which occurred as a unit of 12 American special forces soldiers and 30 Nigerien troops returned from the village of Tongo Tongo, near the border with Mali.

They were attacked by a group of some 50 fighters affiliated with IS and equipped with small arms, grenades and trucks mounted with guns.

The video, set to Islamic chants, shows distressing images of the attack and the soldier wearing the camera being shot to death.

It also depicts the body of at least one other American soldier.