Hiroshima on Wednesday marked the 80th anniversary of the U.S. atomic bombing of the western Japanese city, with many aging survivors expressing frustration about the growing support of global leaders for nuclear weapons as a deterrence.

With the number of survivors rapidly declining and their average age now exceeding 86, the anniversary is considered the last milestone event for many of them.

"There will be nobody left to pass on this sad and painful experience in 10 years or 20 years," Minoru Suzuto, a 94-year-old survivor, said after he kneeled down to pray at the cenotaph. "That's why I want to share as much as I can."

The bombing of Hiroshima on Aug. 6, 1945, destroyed the city and killed 140,000 people. A second bomb dropped three days later on Nagasaki killed 70,000. Japan surrendered on Aug. 15, ending the Second World War and Japan's nearly half-century of aggression in Asia.

Since then, the Japanese government has only paid compensation to war veterans and their families, even though survivors have sought redress for civilian victims. They have also sought acknowledgment by the U.S. government of its responsibility for the civilian deaths.

About 55,000 in attendance

Hiroshima Mayor Kazumi Matsui warned against a growing acceptance of military buildups and of using nuclear weapons for national security during Russia's war in Ukraine and conflicts in the Middle East, with the United States and Russia possessing most of the world's nuclear warheads.

"These developments flagrantly disregard the lessons the international community should have learned from the tragedies of history," he said. "They threaten to topple the peace-building frameworks so many have worked so hard to construct."

He urged younger generations to recognize that such "misguided policies" could cause "utterly inhumane" consequences for their future.

"We don't have much time left, while we face a greater nuclear threat than ever," said Nihon Hidankyo, a Japanese grassroots organization of survivors that won the Nobel Peace Prize last year for its pursuit of nuclear abolishment.

About 55,000 people, including representatives from a record 120 countries and regions attended the ceremony. A minute of silence was held while a peace bell rang out at 8:15 a.m., the time when a U.S. B-29 dropped the bomb on the city.

Japanese Prime Minister Shigeru Ishiba, Matsui and other officials laid flowers at the cenotaph. Dozens of white doves, a symbol of peace, were released after the mayor's speech.

Near Hiroshima's iconic Atomic Bomb Dome under high security, more than 200 protesters gathered, holding posters and flags carrying messages such as "No Nuke, Stop War" and "Free Gaza! No more genocide" while chanting slogans. 

Japan not a signatory to nuclear treaty

Hours before the official ceremony, as the sun rose over Hiroshima, survivors and their families started paying tribute to the victims at the Peace Memorial Park, near the centre of the nuclear blast 80 years ago.

Kazuo Miyoshi, a 74-year-old retiree, came to honour his grandfather and two cousins who died in the bombing and prayed that the "mistake" will never be repeated.

"We do not need nuclear weapons," Miyoshi said.

UN Secretary General Antonio Guterres said in a statement read at the ceremony. Guterres stressed the importance to carry forward the survivors' testimony and message of peace.

"There is hope," Guterres said. The statement noted Nihon Hidankyo's Nobel Peace Prize and countries' commitment to a nuclear free world in its Pact for the Future, an international agreement adopted last year.

In the Vatican, Pope Leo XIV said Wednesday that he was praying for those who suffered physical, psychological and social effects from the atomic bomb on Hiroshima, adding that the event remains "a universal warning against the devastation caused by wars and, in particular, by nuclear weapons."

Japan's government has rejected the survivors' request to sign the Treaty on the Prohibition of Nuclear Weapons or attend its meetings as observers because it is under the protection of the U.S. nuclear umbrella.

Matsui, the city's mayor, in his speech Wednesday, urged Japan's government to sign and ratify the nuclear weapons ban treaty, a request also made by several groups of survivors in their meeting with Ishiba after the ceremony.

Ishiba, in a speech, reiterated his government's pledge to work toward a world without nuclear weapons, but he did not mention the treaty and again indicated his government's support for nuclear weapons possession for deterrence.

At a news conference later Wednesday, Ishiba justified Japan's reliance on U.S. nuclear deterrence, saying Japan, which follows a non-nuclear principle, is surrounded by neighbours that possess nuclear weapons. The stance, he said, does not contradict Japan's pursuit of a nuclear-free world.

Past prime ministers have stressed Japan's status as the world's only country to have suffered nuclear attacks and have said Japan is determined to pursue peace, but survivors say it's a hollow promise.