Japanese Prime Minister Shinzo Abe and US President Barack Obama made a symbolic visit to Pearl Harbor, laying wreaths for the victims of a stealth attack that triggered America's entry into World War Two.
Mr Abe and Mr Obama commemorated the dead at the USS Arizona Memorial, built over the remains of the sunken battleship USS Arizona.
Mr Abe became the first Japanese prime minister to visit the memorial, a centrepiece of the historic site.
The two leaders stood solemnly in front of a wall inscribed with the names of those who died in the 1941 attack and took part in a wreath-laying ceremony, followed by a moment's silence.
"In Remembrance, Shinzo Abe, Prime Minister of Japan" was written on one wreath and "In Remembrance, Barack Obama, President of the United States" on the other. They then threw flower petals into the water.
"We must never repeat the horrors of war," Mr Abe said at the ceremony.
Standing next to Mr Obama, Mr Abe expressed thanks for the "tolerance extended to Japan" as he hailed the power of reconciliation.
Japanese forces attacked Pearl Harbor with torpedo planes, bombers and fighter planes on the morning of 7 Dec, 1941, pounding the US fleet moored there in the hope of destroying US power in the Pacific.
Mr Obama, who is on holiday in Hawaii, and Mr Abe met ahead of the visit to discuss ties between the two former World War Two foes before heading to the site.
Japan hopes to present a strong alliance with the United States amid concerns about China's expanding military capability.
The leaders' meeting was also meant to reinforce the US-Japan partnership ahead of the inauguration of Donald Trump on 20 January, whose opposition to the Trans-Pacific Partnership trade pact and campaign threat to force allied countries to pay more to host US forces raised concerns among allies such as Japan.
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Mr Abe met with Mr Trump in New York in November and called him a "trustworthy leader".
The Japanese leader's visit to Pearl Harbor comes months after Mr Obama became the first incumbent US president to visit Hiroshima, where the United States dropped an atomic bomb in 1945.
Mr Obama called for a world without nuclear arms during his visit there. Mr Trump last week called for the United States to "greatly strengthen and expand" its nuclear capability and reportedly welcomed an international arms race.
