The Japanese city of Nagasaki has marked the 60th anniversary of its destruction by a US atomic bomb at the end of World War II.
Thousands gathered to remember more than 70,000 victims
At least 70,000 people died in the world's second nuclear attack.
A minute's silence was marked at the city's peace park, where survivors tearfully recalled the bombing.
Correspondents say there is fresh controversy over why the attack happened just three days after the bombing of the city of Hiroshima.
Some historians argue that the attack was seen as necessary because Japan had not surrendered.
But others believe that the attack enabled the American military to try out plutonium as a nuclear weapon.
A peace bell rang out as the city marked the exact moment 60 years ago when a US plane dropped the bomb nicknamed "Fat Man" for its rotund shape.
Japan's Prime Minister Junichiro Koizumi took part in the official commemoration, which also saw a memorial Mass in the city's Catholic cathedral.
"This is an occasion to remember the victims, and pray for world peace," he said.
World's first plutonium bombing
Bomb named 'Fat Man' because of rotund shape
Killed 70,000 people outright. City says death toll has now risen to 140,000
Bomb originally destined for city of Kokura, but US plane diverted due to thick cloud
A 74-year-old survivor spoke of her resolve to continue working for the abolition of nuclear weapons.
Nagasaki mayor Iccho Ito asked US citizens whether their security was enhanced by their nuclear arsenal.
"We understand your anger and anxiety over the memories of horror of the 9/11 terrorist attacks. Yet, is your security actually enhanced by your government's policies of maintaining 10,000 nuclear weapons, of carrying out repeated sub-critical nuclear tests, and of pursuing the development of new 'mini' nuclear weapons?" he said.
Mr Ito appealed to them to join hands with others to work together for a peaceful planet free from the threat of the nuclear bomb.
"We are confident that the vast majority of you desire in your hearts the elimination of nuclear arms," he said.
Nagasaki's citizens still question whether the Americans were justified in targeting their city, an important port and industrial centre, for the second atomic attack.
The bomb used plutonium as its core - unlike the one dropped on Hiroshima, which used uranium.
Nagasaki's mayor says he believes they were the victims of what in effect was a deadly nuclear test.
The bomb dropped on Nagasaki exploded with a force equivalent to 21,000 tons of conventional explosive.
Most of those killed in the second attack were melted or burnt to death immediately.
The official death toll is about 70,000 people killed in the immediate aftermath of the bombing, and a further 70,000 who have died of radiation-related illnesses since.
However, correspondents say that Nagasaki's plight has long been overshadowed by that of Hiroshima, where about 140,000 people were killed in the immediate aftermath, and 240,000 are now considered to have died because of the bombing.