SYDNEY — The nearly three-year search for Malaysia Airlines Flight 370 ended Tuesday, possibly forever — not because investigators have run out of leads, but because the countries involved in the expensive and vast deep-sea hunt have shown no appetite for opening another big phase.

Late last year, as ships with high-tech search equipment covered the last strips of the 46,000-square mile search zone, experts concluded they should have been searching a smaller area to the north. But by then, $160 million already had been spent by Malaysia, Australia and China.