Japan is to mark the 70th anniversary of the end of the Battle of Okinawa - one of the bloodiest episodes in the Pacific during World War Two.
PM Shinzo Abe will speak at a ceremony in the southern city of Itoman.
About 80,000 Japanese soldiers died and more than 100,000 Okinawans were killed or committed suicide during the 82-day battle with the Allied forces.
More than 12,000 US troops also died on the island, about 340 miles (550 km) south-west from mainland Japan.
The strategic island was seen by the Allies as a launchpad for an invasion of Japan.
The assault never came as Tokyo surrendered following the atomic bombs dropped on Hiroshima and Nagasaki in August 1945.
Okinawa remained occupied by the US military until 1972, when Tokyo regained control of the island.
However, Japan's southern-most prefecture is still home to about 26,000 US troops and several bases.
A controversial project to move a US air base from an urban area to the coast hasrecently triggered a stand-off between the central authorities in Tokyo and Okinawa's officials.
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