After briefing Japanese officials on how probes into two crashes involving Osprey planes are progressing, the U.S. Defense Department emphasized the safety and capability of the controversial aircraft amid concerns about their planned deployment to Okinawa.

After a meeting Friday in the suburbs of Washington, Pentagon press secretary George Little backed the tilt-rotor transport planes.

"The Osprey is a highly capable aircraft with an excellent operational safety record, which includes more than five years of worldwide deployments and 140,000 flight hours," Little said in a statement.