The United States has proposed a major change in aircraft flight routes for the planned relocation base for U.S. Marine Corps Air Station Futenma in Okinawa that could worsen noise levels and pose risks to residential areas, diplomatic sources said Tuesday.

The proposal, presented during working-level talks Aug. 9 and 10, could trigger fresh opposition in Okinawa as it would allow U.S. aircraft to fly closer to onshore areas than Tokyo had earlier expected under visual flight rules using two runways in a V configuration to be built on the Henoko cape in Nago.

On Monday, Defense Minister Toshimi Kitazawa asked U.S. Ambassador John Roos to maintain the previous flight routes, saying the new routes could provoke stronger opposition among people in Okinawa, but Roos rejected it, the sources said.