The US military said on Friday it was preparing for the biggest land return in Okinawa since 1972, as it faces a surge in opposition to its presence following the arrest of one its civilian contractors for the murder of a local woman.

Okinawa is the US military's key base in Asia. It hosts 30,000 military personnel on bases that cover a fifth of the island.

"We are respectful of the feelings of Okinawans that our footprint must be reduced," said Lieutenant General Lawrence D. Nicholson, the US commander on the island.