Nagasaki has marked 75 years since the United States' use of the atomic bomb on the Japanese city.
The mayor, survivors and other members of the public stood in silence for a minute to mark the moment a B-29 bomber Bockscar dropped a 4.5-ton plutonium bomb, killing 70,000 people.
The commemoration, which had to be scaled back due to the outbreak of COVID-19, took place in Nagasaki Peace Park.
Mayor Tomihisa Taue read a peace declaration, in which he raised concern that nuclear states had in recent years retreated from disarmament efforts.
Instead, they were upgrading and miniaturising nuclear weapons for easier use, he said.
Mr Taue singled out the US and Russia for increasing risks by scrapping the Intermediate-Range Nuclear Forces Treaty.
"As a result, the threat of nuclear weapons being used is increasingly becoming real," he said.
"True horror of nuclear weapons has not yet been adequately conveyed to the world at large."
He also urged Japan’s government and lawmakers to quickly sign the 2017 Treaty on the Prohibition of Nuclear Weapons.
Prime Minister Shinzo Abe has repeatedly refused to sign the treaty.
He has said Japan’s approach is not to take sides, but to serve as a bridge between nuclear and non-nuclear states to encourage dialogue to achieve a total nuclear ban.
Survivors and pacifist groups say Japan is virtually siding with the US and other nuclear states.
Many peace events and survivors talks were cancelled due to the global pandemic.
Shigemi Fukabori was a 14-year-old student mobilised to work at a shipyard when Nagasaki was bombed.
"There is not much time left for us survivors," he said.
"I'm determined to keep telling my story so that Nagasaki will be the last place on Earth to have suffered an atomic attack.
"We don’t want anyone else to have to go through this.
"Nagasaki bears a responsibility as a witness of catastrophic results the nuclear weapon caused to humanity and environment.
"I hope as many people as possible join us, especially the young generations to inherit our baton of peace and keep running."
A mushroom cloud rises after the second atomic bomb was dropped on Nagasaki, August 9, 1945 (Picture: UPI/PA).