When Chiemi Yonashiro was told an object from a United States military helicopter appeared to have fallen onto the nursery where she had dropped off her three-year-old daughter Mimaru just hours earlier, she burst into tears.

Her daughter – and around 70 other children playing at the nursery at the time – were unhurt, but for Mrs Yonashiro, 46, the incident confirmed her conviction that her family was not safe living in southern Japan’s Okinawa region for one uncomfortable reason: the heavy presence of US military.

“Every day we fear that our lives are at risk,” the mother-of-two told the Sunday Telegraph. “I do not want to let my daughter or other children to experiences such strong fears. I don’t want anyone to suffer this way anymore.”

Mrs Chiemi is one of tens of thousands of Okinawa residents who will on Sunday be offered the opportunity to express their views on the longstanding presence of US military in the region in a historic referendum.

Voters will be asked whether they agree with a deeply controversial plan to relocate a US military base from the crowded residential Futenma region to a more remote part of the island – with early polls indicating that as many as 70 per cent will vote no.