Four unexploded bombs which were jettisoned after a botched US-Australian military training mission have been located in the Great Barrier Reef marine park.
The bombs -- two live and two inert -- were located August 16. An investigation into the incident is ongoing and bomb recovery operations are underway.
During a training exercise in July, two Marine Corps AV-8B Harriers were unable to deploy the bombs on their target situated on Township Island bomb range.
"It was not safe to drop the bombs. There were civilian boats right below them," Commander William Marks of the US Seventh Fleet, told the Australian Broadcasting Corporation after the incident, which took place July 16.
Subsequent investigation into why the mission was botched has revealed that the Harriers took off from from an amphibious assault ship stationed in the Coral Sea before the bombing range was cleared for use, according to a report released Wednesday by the Navy Times.
A suitable alternate location to release the bombs on the range could not be established before the Harriers began to run low on fuel, and because the Harriers were unable to land with bombs equipped the ordnance had to be jettisoned, the Navy Times reported.
"The range was fouled and in the interest of safety it was determined by the Australian range personnel that conditions had not been met to allow the safe release of those weapons," Vice Adm. Scott Swift, then-commander of the U.S. 7th Fleet and exercise commander for the operation, said at the time of the incident.
"In the configuration those Harriers were in they were unable to recover aboard ship with that load, so they were going to transit to a jettison area that had been pre-designated," Swift said. "But because of some other instances, there was not a tanker available; they worked hard to release those weapons on the range. They took as much time as they could and as a result were not able to reach that release point."
With the Harriers low on fuel, the mission team was forced to select a place to drop the payload at sea.
After the mishap, the Great Barrier Reef Marine Park Authority said the jettisoned ordnance posed little risk to wildlife and had not been dropped onto a reef. A US Navy spokesperson said the bombs were dropped about 30 km away from the nearest reef in about 50 meters of water, which would not pose a threat to shipping or navigation.
"The incident was deemed by the authority to be low risk to the marine environment and has been addressed as an operational matter since it occurred," a spokesperson for the Great Barrier Reef Marine Park Authority said, according to The Guardian.
"A high priority for the authority is to continue to work with the Department of Defence to identify options for rapid recovery of the ordnances so they pose no risk to the marine park and stakeholders."