U.S. military aircraft and boats are searching for three U.S. Marines who are missing after their tilt-rotor aircraft crashed into the sea Saturday off Australia's east coast, according to a Marine Corps statement.
Twenty-three other people aboard the MV-22 Osprey have been rescued.
The aircraft had been launched from the USS Bonhomme Richard assault ship and was involved in routine operations when it crashed, the statement said.
A White House official said President Donald Trump, who is vacationing at his golf club in Bedminister, New Jersey, was briefed on the incident by his chief of staff, retired Marine Corps General John Kelly.
The aircraft was still in Australia after completing a joint U.S.-Australian military training exercise two weeks ago in Shoalwater Bay.
The biennial exercise involved about 30,000 troops and 200 aircraft. Australian troops are among U.S.-led coalition forces fighting in Afghanistan and Iraq.
The Marine Corps did not say what caused the crash but indicated it is under investigation.
The Osprey is designed to take off like a helicopter and rotate its propellers to fly like a plane. Its development was almost canceled after 23 Marines were killed during a test flight in 2000.
The U.S. military grounded its Osprey fleet in Japan last December after one of them crash-landed into the sea, injuring five crew members.