U.S. Marine Corps MV-22 Osprey aircraft flew over Japan for the first time on Friday in test flights amid persistent safety concerns among local people, following the Japanese government's announcement Wednesday that they are safe to fly.

The first two gray-painted Ospreys took off from the Marines' Iwakuni Air Station in Yamaguchi Prefecture one after the other in the morning. Both returned to the base by noon, without noticeable trouble. Two more took off in the early afternoon.

The first two were seen flying in cruise mode with their twin rotors tilted forward over Shimonoseki in the prefecture.

After test flights around the Iwakuni base, the Marines plan to begin full operation of the Ospreys, which can take off and land like a helicopter and cruise like a fixed-wing airplane, in October at the Futenma Air Station in Okinawa Prefecture.

Many people in Okinawa still oppose the deployment at the Futenma base, located in a crowded residential area, after two crashes of the aircraft overseas earlier this year.

In Iwakuni, about 70 people gathered near the Marine base to protest against the test flights, holding up picket signs against the Osprey deployment. Some of them were also heard shouting, "Go away Ospreys," when the Ospreys took off from the base.