The Japanese city of Nagasaki will commemorate on Monday the 65th anniversary of its atomic bombing amid a mounting momentum to seek a world without nuclear arms.
Nagasaki was destroyed in an atomic inferno three days after Hiroshima, in twin nuclear attacks that made Japan the only country that has ever been hit with atomic weapons.
The United States for the first time sent an envoy to commemorate the Hiroshima bombing on Friday, reflecting US President Barack Obama's push for a world without nuclear weapons.
Its World War II allies Britain and France, both declared nuclear powers, also sent their first diplomats to the ceremony in the western Japanese city in a sign of support for the goal of nuclear disarmament.
The British and French delegations, as well as an envoy from Israel, will also participate in the Nagasaki ceremony for the first time, but Washington has no plan to send an official representative this time.
During the ceremony to start shortly before 11:02 am (0202 GMT), the time of bombing on August 9, 1945, Nagasaki mayor Tomihisa Taue is expected to express his support for US Secretary General Ban Ki-moon's initiative for an international convention to outlaw nuclear arms.
Ban visited Nagasaki a day before the Hiroshima anniversary, where he attended the ceremony also for the first time as the UN chief.
Nagasaki was devastated by a plutonium bomb nicknamed "Fast Man", which claimed lives of more than 70,000 instantly or days later due to burns and radiation sickness.
"Little Boy", a four-tonne uranium bomb, detonated over Hiroshima, killing an estimated 140,000 people.
Both bombs caused a blinding flash and a fireball hot enough to melt sand into glass and vaporise every human near ground zero.
Japan surrendered on August 15, ending World War II in the Pacific.
The United States has never acceded to demands in Japan for an apology for the loss of innocent lives in the atomic bombings, which many Western historians believe were necessary to bring a quick end to the war and avoid a land invasion that could have been even more costly.