The Defense Ministry said Monday that the U.S. military has not broken operational rules between Japan and the United States regarding its MV-22 Osprey transport aircraft, countering Okinawa's claims that they have flown at a low altitude and outside of the designated hours.
The ministry concluded that "there were no clear violations" of the bilateral agreement as it analyzed documents submitted by the local government in Okinawa, together with some 3,000 photos that the ministry's local bureau took near the Futenma Air Station in the city of Ginowan.
The Okinawa prefectural government has argued that the number of violations such as flying outside of the designated hours and at a low altitude over a highly populated residential area has amounted to 318.
Twelve Ospreys have been deployed at the air station since last October despite local opposition and safety concerns.
The ministry said it plans to notify the Okinawa prefectural government of the results, and urge the U.S. military to continue abiding by the rules.
Tokyo and Washington agreed in September that the U.S. military should avoid low-altitude flights above nuclear power facilities and congested areas, and limit night flights after 10 p.m.