Recent crashes involving the U.S. military's latest transport aircraft are fueling an uproar in Japan that could threaten plans to deploy them to the southern island of Okinawa by the end of the year.
Following an uproar on Okinawa and in another city likely to host the Osprey aircraft, U.S. officials were to brief Japanese government representatives in Washington on Friday.
The Osprey craft can fly like a helicopter or an airplane and has been used in combat in Afghanistan and Iraq. But a crash in April killed two Marines and another last week injured five airmen.
Japan's top government spokesman said last week the plan to deploy the aircraft to Japan this year couldn't move forward until Tokyo received assurances of its safety.
While saying the U.S. takes Japan's concerns seriously, a Pentagon spokesman on Thursday said the U.S. stands by the aircraft.
"The Osprey is a highly capable aircraft with an excellent operational safety record," Pentagon press secretary George Little said.
But coming just as Washington and Tokyo were finalizing plans to send the first Ospreys to Okinawa -- where the U.S. military footprint is always a sensitive political issue -- the accidents could not have happened at a worse time.
In hopes of easing longstanding complaints that Okinawa bears too much of the burden of hosting the U.S. troops in Japan, the two governments in April announced that about 9,000 of the nearly 20,000 Marines there will be moved elsewhere.
Crowding around U.S. bases on Okinawa is particularly intense, and opponents of the bases often complain of the danger of accidents involving local residents, noise from training and base-related crime.
The dispute over the Ospreys has renewed those complaints.
"If the two governments force the deployment of these aircraft on Okinawa as scheduled, there will be an explosion of anger," Kantoku Teraya, a national lawmaker from Okinawa, told reporters Wednesday after submitting a petition to Prime Minister Yoshihiko Noda calling for the deployment to be scrapped.
Okinawa's governor has also said he opposes the deployment, and Iwakuni's city assembly on Friday was expected to pass a nonbinding motion saying the accidents have caused "great worry to citizens and great confusion in the city."
Local approval is not essential for the project to go ahead. But the fracas is an embarrassment for Japan's central government, which after Friday's talks in Washington will have to try to sell the plan anew to the host cities. Noda is scheduled to visit Okinawa on Saturday for a World War II memorial.
The $70 million Osprey is the U.S. military's latest-generation transport aircraft.
It combines airplane-like wings with rotors that allow it to take off and land like a helicopter. Its engines roll forward in flight, allowing it to fly twice as fast as a standard helicopter. It has proven itself to be effective in combat in both Iraq and Afghanistan.
But it got off to a bumpy start.
An early version of the Osprey crashed in 1991 and another crash killed seven the following year. In 2000, 19 Marines were killed when an Osprey crashed during a training exercise in Arizona, and a crash in North Carolina killed four Marines in December of that year.
In 2010, three service members and a civilian contractor were killed in the crash of an Air Force version of the aircraft in Afghanistan.
Last week, all five airmen aboard an Air Force CV-22 Osprey were hospitalized after their aircraft crashed in Florida on a training mission at Eglin Air Force Base. The cause in under investigation.
The crash at Eglin occurred just two months after a Marine Corps version of the aircraft, the MV-22 Osprey, went down during a training exercise in Morocco. Two Marines were killed and two others severely injured.
The Pentagon says it does not believe the cause of the crash was mechanical, and it has not grounded its Osprey fleet.