Ferry flights resumed Monday of U.S. Marine Corps MV-22 Osprey transport aircraft from Iwakuni, Yamaguchi Prefecture, to Okinawa, triggering local criticism a week after a fatal U.S. Air Force chopper crash in the prefecture.

The Defense Ministry informed regional governments that ferry flights began of the latest shipment of MV-22s, which had been offloaded from a ship at U.S. Marine Corps Air Station Iwakuni. The eight tilt-rotor planes arrived at Marine Corps Air Station Futenma in Okinawa in the morning after a three-hour flight.

Prime Minister Shinzo Abe again pledged to make every possible effort to relieve Okinawa's burden of hosting the bulk of U.S. military installations in Japan. "It is our policy to give priority to considering the lives of local residents," Abe said.

The eight MV-22s that arrived at Futenma are part of a second 12-Osprey deployment. Two flew earlier to the base.

The marines will have 24 Ospreys at Futenma when the remaining two at Iwakuni arrive. The Ospreys, first deployed to Futenma last fall, are meant to replace aging CH-46 helicopters.

The Osprey ferry flights were halted after an air force HH-60G Pave Hawk helicopter crashed on a mountain Aug. 5 within the boundaries of U.S. Marine Corps Camp Hansen during a training flight, killing one of the four crew members aboard.

The U.S. military is still investigating the cause of that crash.

"It is regrettable that the (latest) deployment comes at a time when people's concerns have yet to be addressed," Atsushi Sakima, mayor of Ginowan, where the Futenma base is located, told reporters.