Toshiyuki Mimaki is exhausted when we meet him.

The 83-year-old sinks into his chair, closes his eyes, and asks us to keep it brief.

But then he starts talking, and his age seems to melt away with the power of his stories.

He is a survivor of Hiroshima’s atomic bomb, a lifelong advocate for nuclear disarmament and, as of last year, a Nobel Peace Prize winner.

But now, on the 80th anniversary of the bombing, he comes with more than just memories – he has a message, and it is stark.

“Right now is the most dangerous era,” he says.

“Russia might use it [a nuclear weapon], North Korea might use it, China might use it.

“And President Trump – he’s just a huge mess.

“We’ve been appealing and appealing, for a world without war or nuclear weapons – but they’re not listening.”

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‘I didn’t hear a sound’

Mr Mimaki was three years old when the US dropped an atomic bomb on the city of Hiroshima.

It was the first time a nuclear weapon had been used in war, and it’s remembered as one of the most horrific events in the history of conflict.

It’s estimated to have killed over 70,000 people on the spot, one in every five residents, unleashing a ground heat of around 4,000C, melting everything in its path and flattening two thirds of the city.

Horrifying stories trickled out slowly, of blackened corpses and skin hanging off the victims like rags.

“What I remember is that day I was playing outside and there was a flash,” Mr Mimaki recalls.

“We were 17km away from the hypocentre. I didn’t hear a bang, I didn’t hear a sound, but I thought it was lightening.

“Then it was afternoon and people started coming out in droves. Some with their hair all in mess, clothes ragged, some wearing shoes, some not wearing shoes, and asking for water.”

‘The city was no longer there’

For four days, his father did not return home from work in the city centre. He describes with emotion the journey taken by his mother, with him and his younger bother in tow, to try to find him.

There was only so far in they could travel, the destruction was simply too great.

“My father came home on the fourth day,” he says.

“He was in the basement [at his place of work]. He was changing into his work clothes. That’s how he survived.

“When he came up to ground level, the city of Hiroshima was no longer there.”

‘People are still suffering’

Three days later, the US would drop another atomic bomb on the city of Nagasaki, bringing about an unconditional Japanese surrender and the end of the Second World War.

By the end of 1945, the death toll from both cities would have risen to an estimated 210,000 and to this day it is not known exactly how many lost their lives in the following years to cancers and other side effects.

“It’s still happening, even now. People are still suffering from radiation, they are in the hospital,” Mr Mimaki says.

“It’s very easy to get cancer, I might even get cancer, that’s what I’m worried about now.”

Tragically, many caught up in the bomb lived with the stigma for most of their lives. Misunderstandings about the impact of radiation meant they were often shunned and rejected for jobs or as a partner in marriage.

Many therefore tried to hide their status as Hibakusha (a person affected by the atomic bombs) and now, in older age, are finding it hard to claim the financial support they are entitled to.

And then there is the enormous psychological scars, the PTSD and the lifelong mental health problems. Many Hibakusha chose to never talk about what they saw that day and live with the guilt that they survived.

For Mr Mimaki, it’s there when he recounts a story of how he and another young girl about his age became sick with what he now believes was radiation poisoning.

“She died, and I survived,” he says with a heavy sigh and strain in his eyes.

He has subsequently dedicated his life to advocacy, and is co-chair of a group of atomic bomb survivors called Nihon Hidankyo. Its members were awarded the Nobel Peace Prize in 2024.

‘Why do humans like war so much?’

But he doesn’t dwell much on any pride he might feel. He knows it’s not long until the bomb fades from living memory, and he deeply fears what that might mean in a world that looks more turbulent now than it has in decades.

Indeed, despite advocacy like his, there are still around 12,000 nuclear warheads in the world in the hands of nine countries.

“In the future, you never know when they might use it. Russia-Ukraine, Israel-Gaza, Israel-Iran – there is always a war going on somewhere,” he says.

“Why do these animals called humans like war so much?

“We keep saying it, we keep telling them, but it’s not getting through, for 80 years no-one has listened.

“We are Hibakusha, my message is we must never create Hibakusha again.”

Eighty years ago today, an American B-29 bomber dropped an atomic bomb on the Japanese city of Hiroshima.

It was the dawn of the atomic age, but the birth of the bomb can be traced beyond the deserts of New Mexico to Britain, five years earlier.

A copy of a hand-typed document, now in the Bodleian library in Oxford, is the first description of an atom bomb small enough to use as a weapon.

The Frisch-Peierls Memorandum was written by two nuclear physicists at the University of Birmingham in 1940.

Otto Frisch and Rudolf Peierls don’t feature in the film Oppenheimer, but their paper is credited with jump-starting the Manhattan Project that ultimately built the bomb.

Both Jewish scientists who had both fled Nazi Germany, they built on the latest understanding of uranium fission and nuclear chain reactions, to propose a bomb made from enriched uranium that was compact enough to be carried by an aircraft.

The document, so secret at the time only one copy was made, makes for chilling reading.

Not only does it detail how to build a bomb, but foretells the previously unimaginable power of its blast.

“Such an explosion would destroy life in a wide area,” they wrote.

“The size of this area is difficult to estimate, but it will probably cover the centre of a big city.”

Radioactive fallout would be inevitable “and even for days after the explosion any person entering the affected area will be killed”.

Both lethal properties of the bombs that would subsequently fall on Hiroshima and Nagasaki, killing around 100,000 instantly and more than 100,000 others in the years that followed – most of them civilians.

Read more:
Hiroshima survivor’s stark warning
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‘The most terrifying weapons ever created’

Those bombs had the explosive power of around 16 and 20 kilotonnes of TNT respectively – a force great enough to end the Second World War.

But compared to nuclear weapons of today, they were tiny.

“What we would now term as low yield nuclear weapons,” said Alexandra Bell, president of the Bulletin of Atomic Scientists, which campaigns for nuclear disarmament.

“We’re talking about city destroyers…these really are the most terrifying weapons ever created.”

Many of these “high yield” nuclear weapons are thermonuclear designs first tested in the 1950s.

They use the power of nuclear fission that destroyed Hiroshima to harness yet more energy by fusing other atoms together.

Codenamed “Mike”, the first test of a fusion bomb in 1952 yielded at least 500 times more energy than those dropped on Japan.

Impractically devastating, but proof of lethal principle.

Variants of the W76 thermonuclear warhead currently deployed by the US and UK are around 100Kt, six times more powerful than the Hiroshima bomb.

Just one dropped on a city the size of London would result in more than a quarter of a million deaths.

The largest warhead in America’s current arsenal, the B83 has the explosive equivalent of 1.2 megatonnes (1.2 million tonnes of TNT) and would kill well over a million instantly.

But modern intercontinental ballistic missiles (ICBMs) are designed to carry multiple warheads.

Russia’s Sarmat 2, for example, is thought to be capable of carrying 10 megatonnes of nuclear payload.

They’re designed to strike multiple targets at once, but if all were dropped on a city like London most of its population of nine million would be killed or injured.

If that kind of power is incomprehensible, consider how many nuclear warheads there now are in the world.

Nine countries – the US, Russia, China, France, the UK, India, Pakistan, North Korea and Israel – have nuclear weapons.

Several others are interested in having them.

The US and Russia have around 4,000 nuclear warheads each – 90% of the global nuclear arsenal and more than enough to destroy civilisation.

According to analysis from the Stockholm International Peace Research Institute, China us thought to have around 600 warheads, but has indicated a desire to catch up.

Beijing is believed to be building up to 100 new warheads a year and the ICBMs to deliver them.

Five more nuclear powers, including the UK, plan to either increase or modernise their existing nuclear stockpiles.

The nuclear arms race that created this situation was one imagined by Frisch and Peierls in their 1940 memorandum.

Given the mass civilian casualties it would inevitably cause, the scientists questioned whether the bomb should ever be used by the Allies.

They wrote, however: “If one works on the assumption that Germany is, or will be, in the possession of this weapon… the most effective reply would be a counter-threat with a similar bomb.”

What they didn’t believe was that the bomb they proposed, and went on to help build at Los Alamos, would ever be used.

Devastated by its use on Japan, Peierls disavowed the bomb and later campaigned for disarmament.

But that work is now as unfinished as ever.

Non-proliferation treaties helped reduce the expensive and excessive nuclear arsenals of Russia and the US, and prevent more countries from building nuclear bombs.

‘Everything trending in the wrong direction’

But progress ground to a halt with the invasion of Ukraine, as nuclear tensions continued elsewhere.

“After all the extremely hard, tedious work that we did to reduce nuclear risks everything is now trending in the wrong direction,” said Alexandra Bell.

“The US and Russia refuse to talk to each other about strategic stability.

“China is building up its nuclear arsenal in an unprecedented fashion and the structures that were keeping non-proliferation in place stemming the spread of nuclear weapons are crumbling around us.”

‘New risks increasing the threat’

The world may have come closer to nuclear conflict during the Cuban missile crisis of 1963, but the fragmented and febrile state of geopolitics now is more dangerous, she argues.

Conflict regularly flares between nuclear armed India and Pakistan; Donald Trump’s foreign policy has sparked fears that South Korea might pursue the bomb to counter North Korea’s nuclear threat; some states in the Middle East are eyeing a nuclear deterrent to either nuclear-wannabe Iran or nuclear armed Israel.

Add to the mix the military use of AI and stressors like climate change, and the view of the Bulletin of Atomic Scientists is the situation is more precarious than in 1963.

“It’s more dangerous, but in a different way,” said Alexandra Bell. “The confluence of all these new existential risks are increasing the threat worldwide.”

A “toxic workplace culture” was one of several contributing factors that led to the implosion of the Titan submersible on its way to the Titanic, a report has said.

The US Coast Guard Marine Board of Investigation (MBI) said in its report into Oceangate – the private company that owned the submersible – that “the loss of five lives was preventable”.

Titan operator Stockton Rush, who founded OceanGate; two members of a prominent Pakistani family, Shahzada Dawood and his son Suleman; British adventurer Hamish Harding; and Titanic expert and the sub’s pilot, Paul-Henri Nargeolet, died on board.

On Tuesday, a 335-page report into the disaster went on to make 17 safety recommendations, which MBI chairman Jason Neubauer said will help prevent future tragedies.

“There is a need for stronger oversight and clear options for operators who are exploring new concepts outside of the existing regulatory framework,” he said in a statement.

The investigation’s report found that the submersible’s design, certification, maintenance and inspection process were all inadequate.

It also highlighted the fact that the company failed to look into known past problems with the hull, and that issues with the expedition were not monitored in real time and acted upon.

‘Intimidation tactics’

The report states that contributing factors to the disaster included OceanGate’s safety culture and operational practices being critically flawed, and an “ineffective whistleblower process” as part of the Seaman’s Protection Act – a US federal law designed to protect the rights of seamen.

The report adds that the firing of senior staff members and the looming threat of being fired were used to dissuade employees and contractors from expressing safety concerns.

It alleges: “For several years preceding the incident, OceanGate leveraged intimidation tactics, allowances for scientific operations, and the company’s favourable reputation to evade regulatory scrutiny.

“By strategically creating and exploiting regulatory confusion and oversight challenges, OceanGate was ultimately able to operate Titan completely outside of the established deep-sea protocols, which had historically contributed to a strong safety record for commercial submersibles.”

Numerous OceanGate employees have come forward in the two years since the implosion to support those claims.

OceanGate suspended operations in July 2023 and has not commented on the MBI’s report.

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The Titan sub went missing on its voyage to the wreck of the Titanic.

After five frantic days of searching, the wreckage was eventually found on the ocean floor roughly 500m from the sunken Titanic.

The MBI investigation was launched shortly after the disaster.

During two weeks of testimony in September 2024, the former OceanGate scientific director said the Titan malfunctioned during a dive just a few days before it imploded.

OceanGate’s former operations boss also told the panel the sub was a huge risk and the company was only focused on profit.

The board said one challenge of the investigation was that “significant amounts” of video footage evidence that had been captured by witnesses was not subject to its subpoena authority because the witnesses weren’t American citizens.