The United States has begun sharing with Japan the conclusions into an accident involving a V-22 Osprey as part of the conditions outlined by Tokyo to allow the Marine Corps to operate the tilt-rotor aircraft on Okinawa.

Marine Commandant Gen. James Amos released a statement yesterday saying that the Japanese have been informed of the inquiry into a MV-22 crash in Morocco in April that killed two Marines.  That was followed by an accident in Florida involving an Air Force version known as the CV-22. Four people were injured.

The Japanese government, along with Okinawa residents who are historically weary of the Marine presence on the island, are worried the Ospreys pose a safety hazard, a concern that grew after those recent accidents.

The United States has sought to assure the Japanese that the aircraft are safe and bring enhanced capability to the alliance between the two countries and to Asia-Pacific operations. Washington has emphasized that the Ospreys, built by a partnership between Boeing [BA] and Textron [TXT] unit Bell Helicopter, have come a long way since being plagued by development problems in the 1990s that produced several fatal accidents and caused the program to be put on hold.

“Historical data gathered from the past 10 years of flying proves that the Osprey is one of the safest aircraft flying in the U.S. inventory,” Amos said in a lengthy statement. “Having surpassed 100,000 flight hours last year and over 13 highly successful combat deployments to both Iraq and Afghanistan, the airplane has proven its mettle in some of the most demanding environmental conditions imaginable–including having been shot at and hit on several occasions during combat.“

“Many are unaware that this notable safety record is not the product of mere chance,” he added. “It reflects a rigorous and lengthy design/development process as well as a continuous effort to deliver material improvements, software updates, and enhanced pilot training.”

“These extensive efforts are consistent with the US military’s longstanding interest in the safe operation of equipment around the world,” he said. “This information, along with the facts from our Morocco mishap, is being shared this week with the Japanese assessment team that is currently examining the technical capabilities of the aircraft. “

The V-22s are slated to replace the legacy CH-46 Sea Knight helicopters, and 12 of them arrived in Iwakuni, Japan on July 23. They are eventually to be stationed at Marine Corps Air Base Futenma in a densely populated area of Okinawa. Amos said the Marines will try to avoid flying the aircraft over populated areas.

“It is my intent that Marine Osprey pilots will make every effort to minimize flying over heavily populated areas in Japan,” he said.

The Pentagon has said that the V-22’s ability to fly at higher altitudes, faster speeds and longer ranges is a significant capability upgrade over the CH-46s to respond to military contingencies, disasters and for humanitarian operations.

The issue was a subject of a meeting in Washington earlier this month between Defense Secretary Leon Panetta and his Japanese counterpart, Satoshi Morimoto. Morimoto, who flew on a V-22 during the visit, reiterated that his government wanted to assess the accidents in Morocco and Florida before green lighting operations on Okinawa.

“The United States will give us the report of the investigations with regard to what happened in Florida and Morocco as soon as possible, and until we confirm the safety of it the United States will refrain from flying the Osprey,“ Morimoto said through a translator.