The city of survivors is losing its authority

Hiroshima today is a city of 1.2m people, the tenth-largest municipality in Japan, with a riverfront promenade, an international airport and a thriving regional economy. The wristwatch that stopped at 8.15am on 6 August 1945 still lies behind glass in the Peace Memorial Museum. The city has been rebuilt, repopulated and made prosperous. That is the story the commemoration ceremonies on Thursday, the 81st anniversary of the atomic bombing, will tell once more.

The more disquieting story is that the world Hiroshima was meant to save is retreating from the very norms the city exists to defend. And nowhere is the contradiction sharper than in Japan itself.

At the ceremony in the Peace Memorial Park, the decades-long decline in nuclear arsenals is reversing. Nuclear sabres are being rattled once again.

Then the prime minister took the stage.

Her phrasing was carefully calibrated. But the subtext was plain. Her government has just approved a defence budget of 9trn yen ($58bn).

The irony was not lost on the survivors in the audience. The youngest were too young to remember clearly. Those who do carry the memory have asked, repeatedly and without hearing, for Japan to sign the Treaty on the Prohibition of Nuclear Weapons. The government refuses. It needs Washington's nuclear umbrella, and the Americans will not offer one alongside a Japanese pledge to ban the weapons they are meant to be shielding against.

This is not merely a problem of Japanese politics. It is the structural fault line of the postwar order. The countries that preach nuclear disarmament from the stage in Hiroshima are the same ones building arsenals behind closed doors. The United States, Russia and China are all expanding their stockpiles. France and the United Kingdom are modernising theirs. North Korea continues to test. Pakistan and India upgrade. The world's nuclear-armed states have no incentive to disarm unilaterally. The system is a prisoner's dilemma: every state arms because every other state arms. Hiroshima's appeal to conscience is a message that rational statecraft has no mechanism to act upon.

Yet the Japanese case has its own peculiar bite. No other capital of a nuclear-armed state hosts an annual ceremony in which the premier stands between a plea for abolition and a budget for rearmament. That position — moral witness and military partner — was sustainable when the Cold War provided a shared framework. It is becoming untenable as the framework dissolves.

To be sure, Japan's rearmament has drivers that have nothing to do with Hiroshima's symbolism. China's military modernisation, its carrier drills near Japan's southwest islands and its rhetoric on Taiwan present a genuine strategic challenge. Prime Minister Takaichi announced in April a near-total lifting of arms-export restrictions, opening the door for firms such as Mitsubishi Heavy Industries to sell lethal equipment to partner countries.

The rearmament programme also has practical problems. It is building an export strategy on an industrial base that is still learning to compete at home.

None of this means Japan should remain pacifist in the face of real threat. The country has a legitimate interest in territorial defence and in contributing to the security of the region. But the arithmetic of nuclear policy is independent of the arithmetic of conventional defence. Japan can build missiles and buy frigates without abandoning the moral claim that nuclear weapons are unacceptable. That claim is not sentiment. It is a constraint on escalation that even nuclear-armed states, when pressed, say they uphold.

The deeper problem is not Japan's defence budget. It is the erosion of the idea that the bombing of Hiroshima taught anything beyond the point that the bomb works. The survivors knew more than that. They knew the bomb was not a deterrent; it was an endpoint. The lesson was that a technology capable of obliterating a city in seconds should be treated as a civilisational boundary, not as a bargaining chip.

The ceremony on Thursday included a minute of silence at 8.15am, with the peace bell ringing across the memorial park. The ritual is dignified. But rituals without consequences are performances. Hiroshima's authority as a moral capital depends on the countries that listen taking the message seriously — not just the ones who send delegations to nod at the cenotaph, but the ones who set the rules. Japan's choice matters most, because it is the one country that cannot separate the memory of the bomb from the politics of its own defence. Better to honour the silence than to fill it with missiles.