The US Defense Department said Tuesday that two US soldiers were killed in northern Iraq on Sunday.
Colonel Robert Manning, a Pentagon spokesman, said a "flaw" in US Army artillery was behind the deaths of the two soldiers, adding that the army was investigating the incident, which also wounded five other soldiers.
"An artillery unit of the army was on a mission to respond to the location of a pre-emptive organization ... when there was a defect that caused the injury of 7 soldiers."
Manning said there was no indication that the terrorist organization had any links to the deaths of the soldiers, and that the five soldiers were not life-threatening.
The Pentagon refused to give further details. It was not clear exactly what the "imbalance" had taken place.
The wounded soldiers were part of a US-led coalition fighting the terrorist organization in Iraq.