(Bloomberg) -- The US rejected a Japanese government request to ground its fleet of CV-22 Osprey aircraft in the country after a deadly crash, a rare public disagreement between the treaty allies.

The tilt-rotor aircraft in Japan operate “only after undergoing thorough maintenance and safety checks,” Pentagon deputy spokeswoman Sabrina Singh said in a statement. The statement made no reference to a Japanese government request, made after the Nov. 29 crash, that the US suspend Osprey operations in Japan until their safe operation can be ensured. 

“We have good communications between our senior leaders and are in constant dialogue regarding aviation safety and other safety-related issues,” Singh said. 

Japan’s Ground Self-Defense Force has grounded its own fleet of Ospreys. The craft has been a source of strain between the two countries in the past, with demonstrators protesting the use of the aircraft in Japan over its safety record more than a decade ago.

Singh’s statement said Osprey flights have been suspended in the Air Force unit that flew the crashed plane. Separately, the Air Force said the search continues for the crew lost in the crash. One set of remains was recovered while the other seven members of the crew are missing, it said.

In August, three US Marines were killed and five others critically injured after a V-22 Osprey went down while performing drills off the coast of Darwin in Australia’s Northern Territory. Prior incidents with the V-22 Osprey included a crash in 2000 that killed 19 Marines in Arizona. The accident was blamed on pilot error.

The Osprey was developed by Bell Helicopter and Boeing Helicopters.

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