The port of Nago has been the scene of intensive campaigning over the past few weeks. Those in favour of the heliport say it will be good for the local economy where there's high unnemployment.

If the residents vote yes, the government will give the town funds for development. But those against the base say if it's accepted it will give a signal that the people of Okinawa are in favour of US military bases.

Resentment against the large US military presence on Okinawa runs deep since a schoolgirl was raped by three US servicemen three years ago. Many Okinawans have campaigned to have the bases removed completely or significantly reduced.

Many also lay claim to the land where the bases are built and others complain about the noise from the aircraft and general disruption the bases cause. But the Japanese government is obliged to provide facilities for US forces under the security alliance.

The offshore heliport may be the only answer as other regions of Japan have refused to take new bases. The structure of the heliport has yet to be designed but it would be about three kilometres from the coast and would have room for about 60 helicopters.