The US has dropped bombs on the Great Barrier Reef.

U.S. fighter jets dropped four bombs on the Great Barrier Reef off Australia's coast.

The bombing of the reef occured during a training exercise that went wrong, it has been revealed.

The jets dropped four bombs. Two were inert and two were "unarmed". The bombs the U.S. jets dropped went into about 165 feet of water, "away from coral", to, theoretically, minimize the damage to the Great Barrier Reef, which is a World Heritage Site.

The US navy said that the jets were supposed to bomb an island range nearby, but the mission went wrong and was aborted.

It occurred during a training exercise involving US and Australian military personnel. The exercise was called Talisman Saber.

The AV-8B Harrier jets were supposed to bomb a target range on Townshend Island, but it wasn't safe to do so as there were civilian boats nearby.

However, the jets were also short on fuel and could not land loaded.

"It was not safe to drop the bombs. There were civilian boats right below them," Commander William Marks of the US Seventh Fleet told press.

Thus, the bombs were dropped off the coast of Queensland in the marine park. The four bombs weighed 500 lbs each. None exploded, but the military claims they do not pose a hazard to shipping and that they will update charts to show the bombs.

US Navy says, and charts are to be updated to show the unexploded ordnance.

"There is minimal environmental impact," said Cmdr Marks. "It is a safe situation for the environment, for shipping, for navigation."

The US Navy plans to leave the bombs in place for right now, but may recover them at some point if the Australian government wants it.

"If the [Great Barrier Reef] park service and the government agencies of Australia determine that they want those recovered, then we will coordinate with them on that recovery process," said Seventh Fleet spokesman Lt David Levy.

The Great Barrier Reef is a 1,700 mile stretch along Australia's eastern coast and the world's largest coral structure.