A search is ongoing to find four missing air crew members after an Australian army helicopter landed into waters off the Queensland state coast on Friday.
The MRH-90 Taipan helicopter went down near Hamilton Island while conducting joint military exercises with the United States, officials said.
Defence minister Richard Marles told reporters: “Defence exercises, which are so necessary for the readiness of our defence force, are serious. They carry risk.
“As we desperately hope for better news during the course of this day we are reminded about the gravity of the act which comes with wearing our nation’s uniform."
A rescue helicopter reported spotting debris on Saturday near Dent Island in the Whitsunday Islands group.
The Taipan was taking part in Talisman Sabre, a biennial joint US-Australian military exercise that is largely based in Queensland.
Mr Marles said the helicopter ditched, which refers to an emergency landing on water.
He said it was taking part in a mission that involved a second helicopter, which immediately started a search and rescue operation.
US military personnel are also taking part in the search.
The missing helicopter had just dropped off two Australian commandos before it hit the water, Australian Broadcasting Corp reported.
It is the second emergency involving an Australian Taipan this year, after one ditched into the sea off the New South Wales state coast in March.
That helicopter was taking part in a night-time counterterrorism training exercise when it ran into trouble. All 10 passengers and crew members were rescued.
Australia announced in January its army and navy would stop flying the European-built Taipans by December 2024, 13 years earlier than originally planned, because they had proved unreliable.
US defence secretary Lloyd Austin was in Brisbane for a meeting on Saturday and is due to travel with Mr Marles to north Queensland on Sunday to see the exercise.
The exercise has been paused by the search.
Mr Austin and US secretary of state Antony Blinken paid tribute to the missing air crew at the outset of a meeting with their Australian counterparts.
Mr Austin said: “It’s always tough when you have accidents in training, but... the reason that we train to such high standards is so that we can be successful and we can protect lives when we are called to answer any kind of crisis.
