Prime Minister Anthony Albanese has offered his thoughts to the families of four missing soldiers after an army helicopter crashed.
There are grave fears for Captain Daniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs.
Their Taipan MRH-90 helicopter crashed near Queensland's Hamilton Island on Friday morning.
The chopper had been conducting joint military training as a part of Exercise Talisman Sabre.
Mr Albanese said the tragedy was a reminder of the danger faced by the nation's defence force personnel.
"Each and every day is one which carries some risks," he told ABC radio on Monday.
"Our thoughts today remain very much focused on the families, the friends but also the colleagues as well, who will be going through a difficult time."
Some debris from the stricken aircraft was found on Saturday but the main body is yet to be recovered.
"We're focused on bringing them home, supporting their families and getting to the bottom of what happened," Australian Army chief Simon Stuart said.
Defence Personnel Minister Matt Keogh said the investigation into the crash was yet to determine the cause.
"Our key focus is on the ongoing search in supporting a family at this time," he told Sky News.
Mr Keogh said the Taipan, which is coming out of service at the end of next year, may not be retired early after the crash.
"We'll need to see what the causes are and whether additional mitigations need to be put in place before it can resume operation," he said.
Specialist navy divers have joined Queensland police and crews from HMAS Brisbane, HMAS Adelaide and USS Miguel Keith in their search for the missing Taipan.
An exclusion zone is in place south of Hamilton Island, from the southern tip of Long Island east to Perseverance Island, south to Cole Island and west to the mainland at Round Head.
Members of the public who find crash material have also been urged to contact investigators.
Defence Force chief General Angus Campbell thanked Australian and international defence personnel assisting in the search.
"We'll do everything we can to ... see the search and rescue effort undertaken as expeditiously and as effectively as possible," he said.
Forty-seven MRH-90 helicopters have been grounded until further notice.
It is the second time an Australian MRH-90 has been involved in an emergency this year after a Taipan ditched off the NSW south coast in March.
General Campbell would not discuss the immediate future of the MRH-90 helicopters, instead saying the focus remained on the missing men.
"There will be an investigation as there always is in these circumstances and we will look to that to understand what has occurred here," he said.
The Talisman Sabre training operation involves defence forces from Australia, the United States and other allies.
The joint exercises, mostly being held in regional Queensland, resumed late on Saturday in the Northern Territory and Western Australia after an initial pause.
© AAP 2023