A joint Australian-US Navy dive team recovered bombs dropped by American forces on the Great Barrier Reef during a training exercise in a delicate deep-sea operation, officials said Sunday.
The divers attached balloons to pull the two unarmed GBU-12 laser guided bombs to the surface in a two-day deepwater operation involving strong tides, United States and Australian officials said in a statement.
"The United States and Royal Australian Navies should be congratulated on the successful recovery and disposal of the ordnance, while ensuring that all environmental and safety requirements were met," said Lieutenant General Ash Power, Australian chief of joint operations.
Two other pieces of inert ordnance—cement-filled BDU-45 dummy bombs used for training with no explosive elements—were left on the ocean floor due to the "difficult diving conditions".
All four bombs were jettisoned in the waters of the Great Barrier Reef Marine Park by two US AV-8B Harrier jets during bilateral war games with Australian forces last month after civilian boats strayed into the intended drop zone.
They were found by minesweeper HMAS Gascoyne a fortnight ago using a remote-controlled submersible equipped with sonar.
After they were brought to the surface and underwent safety inspection the two unarmed bombs were taken to a nearby official ordnance demolition beach and detonated.
Russell Reichelt, head of the Great Barrier Reef Marine Park Authority, said survey images had confirmed the bombs landed "on a sandy bottom, well away from coral and any sensitive habitat".
"We supported the US Navy's decision to leave the inert rounds on the seafloor due to the challenging and potentially unsafe diving conditions—these devices are not actual ordnance and pose no risk to people or the environment," said Reichelt.
"Our personnel will continue to monitor the area in the coming days for any potential impacts following the recovery and disposal part of the operation."
They were found 30 kilometres from the nearest coral reef and 50 kilometres from the coastline "well away from any sensitive habitat".
Explore further: Gulf health 5 years after BP spill: Resilient yet scarred