The United States has confirmed that four crew members were killed in a KC-135 refueling plane crash over western Iraq on Thursday.
The incident occurred after an incident involving another plane, but US Central Command has ruled out hostile or friendly fire as the cause of the crash.
The identities of the service members are being withheld until 24 hours after next of kin have been notified, according to CENTCOM.
The US military has been involved in a campaign against Iran, and the crash comes amid intense drone and military exchange over the Middle East.
The KC-135 is at least the fourth US military aircraft lost during the war in the Middle East, after three F-15s were shot down by friendly fire over Kuwait.
