The Pentagon says the two U.S. service members who were recently killed in Iraq died in an artillery "mishap."
"An army artillery section was conducting a counterfire mission against an ISIS mortar site when a mishap occurred, injuring seven soldiers," Pentagon spokesman Colonel Rob Manning said on August 14, using an acronym for the extremist group Islamic State (IS).
Two of the troops later died.
The U.S.-led coalition fighting the IS militants said on August 13 that initial reports indicated the casualties did not occur as a result of contact with the enemy, although it did not elaborate.
The Amaq news agency, which is linked to IS, claimed rockets fired by the group resulted in several casualties among U.S. troops in northern Iraq.
The agency said the attack targeted a village east of the IS-held town of Tal Afar.
IS fighters have been driven from much of the territory they captured in 2014 from government forces, including the major northern city of Mosul.
But they still control some areas, including Tal Afar, west of Mosul.
The iCasualties.org website, which lists coalition casualties in Iraq and Afghanistan, reports that 11 U.S. soldiers have been killed in Iraq in 2017.