US miliary officials have effectively confirmed they don't expect to find three Marines missing after their aircraft crashed off Queensland's coast alive and say recovery attempts could drag on for months.
Authorities on Sunday suspended search and rescue operations less than 24 hours after their aircraft crashed off Queensland's coast while trying to land.
The US Navy and Marine Corp - with help from the Australian Defence Force - are now focusing their efforts on salvage and recovery, which they warn could take several months.
The three missing marines' next-of-kin have been notified, the Marine base Camp Butler in Japan said in a statement.
The MV-22 Osprey had launched from the USS Bonhomme Richard and was conducting regularly scheduled operations on Saturday when it crashed into the water, Camp Butler said.
The ship's small boats and aircraft immediately responded in the search and rescue efforts, and 23 of 26 personnel aboard the aircraft were rescued.
"Recovery and salvage operations can take several months to complete, but can be extended based on several environmental factors," Camp Butler's statement said.
"The circumstances of the mishap are currently under investigation, and there is no additional information available at this time."
The crash occurred around 4pm on Saturday off Shoalwater Bay, where the biennial Talisman Sabre joint US and Australian military training exercise is underway.
It had taken off from the USS Bonhomme Richard, an amphibious assault ship, and was on regularly scheduled operations when it hit the water in what the US military described as a "mishap".
The Queensland Ambulance Service says it transported one of the marines involved to Rockhampton Hospital with a fractured leg but it is not known how many others onboard were injured.
US President Donald Trump, who has just begun a 17-day "working vacation", at his New Jersey golf club, had been briefed on the incident by his new chief of staff John Kelly, a White House official told reporters.
Minister for Defence Marise Payne confirmed in a statement late on Saturday night that no Australian Defence Force personnel were on board the aircraft.
"Our thoughts are with the crew and families affected," she said.
Queensland Premier Annastacia Palaszczuk offered her government's support.
"On behalf of all Queenslanders, our prayers are with those US military personnel involved in the incident," she said in a statement.
The incident is the 10th known crash involving an Osprey, a tilt rotor aircraft that takes off and lands like a helicopter but flies like an aeroplane, since 1991, and the sixth since it officially came into service in 2007.
It is also potentially the worst military accident in Australia since the 1996 Black Hawk tragedy that killed 18 servicemen near Townsville.