ISTANBUL

All six crew members aboard a US KC-135 refueling aircraft that crashed in western Iraq on Thursday were killed, the US Central Command (CENTCOM) said on Friday.

"The circumstances of the incident are under investigation. However, the loss of the aircraft was not due to hostile fire or friendly fire," CENTCOM said in a statement.

The identities of the service members are being withheld until 24 hours after next of kin have been notified, the command added.

The command said on Thursday that a refueling aircraft was lost over Iraq during its Operation Epic Fury against Iran, which began last month.

Two aircraft were involved in the incident, CENTCOM said, adding one of the aircraft went down in western Iraq, and the second landed "safely."

Earlier, addressing a news conference alongside Gen. Dan Caine, chairman of the Joint Chiefs of Staff, US Defense Secretary Pete Hegseth said war is "hell."

"War is chaos and as we saw yesterday with the tragic crash of our KC-135 tanker, bad things can happen," Hegseth said.

Caine, for his part, said: "Those are very, very, very tough days when that knock comes on the door."

The recent fatalities raise the number of US troops killed since the operation began on Feb. 28 to 13.