A ship carrying the U.S. military's latest transport aircraft Osprey arrived in Japan on Monday morning amid protests over safety issues.

Workers began unloading and assembling the 12 MV-22 Osprey aircraft in the city of Iwakuni soon after the ship arrived, according to reports. The U.S. plans to deploy the newer tilt- rotor aircraft to Okinawa to replace CH-46 helicopters.

Iwakuni Mayor Yoshihiko Fukuda told reporters after the ship's arrival that he will lodge a protest with the central government. "We have been urging that it not be allowed into the port until safety is confirmed," he said. "We feel distrust and indignation that (our message) did not reach the state."

Though the Ospreys will only be in Iwakuni shortly, its deployment plan has become the latest uniting point for U.S. base opponents.

Both the mayor of Iwakuni and the governor of Okinawa said that they do not support even temporarily hosting the aircraft. Protesters on Monday held a sit-in outside the base where the Ospreys are to be transported to, according to local media.