The Osprey -- which can operate like a helicopter or a fixed-wing turboprop plane -- disappeared on November 29 near the island of Yakushima, sparking an intense search for survivors.

"The US military transitioned search and rescue operations to search and recovery operations," meaning "survivors are unlikely," the Air Force Special Operations Command said in a statement.

"Of the eight airmen, the remains of three airmen have been recovered, the remains of another three airmen have been located and are in the process of being recovered, and the remains of two airmen are still being located," it said.

US President Joe Biden offered condolences to the families of the military personnel in a statement on Tuesday.

"Jill and I are praying for the families and friends who lost a loved one in this terrible accident," Biden said, referring to the first lady. "Our entire nation mourns this tragic loss."

Osprey aircraft have suffered a string of fatal accidents, including a crash in northern Australia that killed three US Marines in August, and another in Norway during NATO training exercises last year that left four dead.

Three Marines were also killed in 2017 when another Osprey crashed off Australia's north coast and 19 Marines died when their Osprey crashed during drills in Arizona in 2000.

The United States temporarily grounded the aircraft in Japan in 2016 after an Osprey crash-landed off Okinawa, sparking anger among locals.

Japanese Defense Minister Minoru Kihara said on Thursday he had asked the US military to again suspend Osprey flights -- except for search-and-rescue operations -- and that Japan's military had halted using its own Ospreys pending safety checks.

But the Pentagon said the following day that only the unit of the crashed CV-22 had stopped flying. It was not immediately clear if that halt was still in effect.