A video was posted on an extremist Islamist Web site Tuesday showing a US soldier being shot in Iraq while guarding an armored vehicle.
The militant Islamic Army in Iraq issued a statement saying one of its snipers killed the soldier in Baghdad on Monday.
It was not immediately possible to verify the statement and it was unclear if the soldier had died.
"This morning, Oct. 24, our sniper company managed to shoot an American soldier in Baghdad and kill him with God's grace," the statement claimed.
The grainy footage showed a soldier standing next to what appeared to be an armored personnel carrier before hunching over and falling to the ground.
White smoke was seen rising from his stomach area.