Marine Corps officials in Okinawa announced Sunday it had suspended rescue efforts for the three Marines still missing from the crash.
"It's been a rough couple of days", said Robert Cross, father of 1 Lt. Benjamin Cross, who said his 26-year-old son was a skilled and dedicated pilot.
The deployment of Ospreys in Japan is unpopular with local residents, and Japanese Defence Minister Itsunori Onodera has asked the United States to ground its Japan-based fleet until the cause of this crash is known.
Okinawa residents near U.S. Marine Corps Air Station Futenma, where the Ospreys are deployed, are concerned about the safety of the aircraft, the development of which was marred by dozens of fatalities.More news: Inter try to end Man United's Ivan Perisic hopes
The Pentagon has not yet identified the third missing Marine.
The MV-22 Osprey involved in the mishap had launched from the USS Bonhomme Richard and was conducting regularly scheduled operations when it crashed into the water, the statement said. Twenty-three other service members aboard the tilt-rotor aircraft were rescued.
The MV-22 Osprey had taken off from the USS Bonhomme Richard, an amphibious assault ship.
The aircraft was assigned to Marine Medium Tiltrotor Squadron 265 and was operating with the 31st Marine Expeditionary Unit, or MEU.More news: Venezuela government says arrests made after reports of military uprising
Twenty-three of the 26 military personnel had been rescued, but three U.S. Marines are still missing. Green Bay. Something then caused the Osprey to plunge into the water about 30 miles off the east coast of Australia.
Australian authorities said no Australian personnel were on board. The crash, which happened during a nighttime refueling at sea, enflamed protests and renewed calls for Ospreys to be expelled from the island.
The Osprey was in Australia for a joint military training exercise between the two countries. And in January, three US soldiers were wounded in the "hard landing" of an Osprey in Yemen.More news: GDP in European Union , eurozone up 0.6 percent in 2nd quarter