There are grave fears for the lives of the crewmen, identified as Captain Daniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs.
They were on board the Taipan helicopter when it crashed in waters near Queensland's Hamilton Island about 10.30pm on Friday.
The MRH-90 helicopter had been conducting joint military training as a part of Exercise Talisman Sabre.
Some debris from the stricken helicopter was found on Saturday but the main body of the aircraft 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.
Specialist navy divers have joined Queensland police and crews from the HMAS Brisbane, HMAS Adelaide and USS Miguel Keith in their search for the missing Taipan.
An exclusion zone is in place in waters 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 the Australian and international defence personnel assisting in the search efforts.
"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 into waters 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 West Australia after an initial pause.
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