All these years later the fallout remains, as do the cancers and devastated lives of wholly innocent people.

A quarter of a century on and another group of innocent people, this time hundreds of conscripted British soldiers, were exposed to the horrific realities of the nuclear bomb.

They were ordered by their commanding officers to act as human guinea pigs, told to stand and watch test explosions in the Pacific.

In a poignant reminder last week of the obscenity of nuclear weapons these veterans finally defeated Ministry of Defence attempts to have their case for compensation thrown out.

After 50 years of the ministry's refusal to admit responsibility for their lives of suffering - a stance which persisted under both Labour and Conservative governments alike - the Supreme Court has given them the green light to challenge their treatment.

Despite these reminders of the dangers of nuclear war, and a string of nuclear accidents and disastrous pollution, the five permanent members of the UN security council and India, Pakistan and Israel all hold nuclear weapons.

All of them want to keep developing and upgrading their systems, riding roughshod over nuclear Non-Proliferation Treaty commitments and widespread acknowledgement that their arsenals are indiscriminate weapons of WMD.

They kill military and civilians alike, before laying waste to land and lives for decades afterwards.

There are some glimmers of hope towards disarmament.

North Korea announced on Monday that it wants to see a resumption of unconditional six party talks on disarmament including activation of the 2005 plan to dismantle its programme altogether.

There are many reasons for this welcome development. Not least among them is united diplomatic pressure, but the country also has an enormous economic imperative. A nation with an underfed and malnourished population can hardly justify spending precious resources on these weapons.

The same argument applies elsewhere just as strongly.

The US, the world's biggest debtor at $14.1 trillion and rising, has watched the final episode of the Capitol Hill soap opera.

Politicians struck a deal to protect the wealthiest citizens and corporations from any tax rises while making sure that the debt is paid for by cutting public spending on the poorest.

The US world military role will also be underwritten - for now.

On this side of the Atlantic the British government has adopted much the same kind of posture, albeit on a smaller scale.

Britain developed its own nuclear weapons in secret in the aftermath of World War II.

Then Labour prime minister Clement Attlee did not even inform the 1949 Cabinet of its existence.

The Conservatives later realised that maintaining a separate nuclear capability was too expensive for post-war, post-empire Britain.

To keep up appearances the government enthusiastically promoted Nato and eventually bought into the US Polaris system in a 1963 deal.

We have been a fictional holder of "independent" nuclear weapons ever since.

The US was invited in to use military bases to maintain and, if it decided to, launch nuclear weapons from.

In recent years the weapons lobby has been hard at work peddling a new generation of nuclear WMD, trying to persuade Parliament of the need to maintain a "global role."

The last Labour government maintained that Britain needed to replace Trident and forced a vote through Parliament. Over 100 Labour MPs dissented and voted against its position. However the Tories strongly backed nuclear weapons and the Liberal Democrats called feebly for "no like-for-like replacement" of the system.

Since then the MoD has accepted that procurement will cost £25 billion with £3bn already earmarked to be spent between now and 2016 on design and £500 million on long-lead items such as specialist steel.

Estimates of the lifetime costs of the new system now hover in the region of £100bn.

The "main gate" decision on whether to proceed with the entire project will follow the 2015 election and be taken early in the new Parliament.

The year 2016 is no doubt circled in red on defence department calendars.

As for the Liberal Democrats' stance on "no like-for-like" WMD system, the MoD has agreed to carry out a review on possible alternatives.

The problem is that it will only consider alternatives that include maintaining nuclear weapons.

Labour under Blair and Brown backed nuclear weapons.

Ex-defence secretary Hoon even considered ending any "no first use" rule.

But opposition to nuclear weapons and Trident remains strong within the Labour Party. Alongside MPs, many party activists are also supporters of the Campaign for Nuclear Disarmament.

The policy review initiated by Ed Miliband provides an opportunity for reopening the whole debate.

In fact a large number of Labour MPs have signed a statement declaring: "We regret the coalition has committed to Trident replacement.

"At a time of severe spending cuts across the public sector, there has been no critical assessment of Trident's role in addressing the UK's security threats.

"No case for replacing Trident has been made. The Labour Party should commit to a defence review that considers non-replacement and disarmament of Trident.

"We must play our role in building momentum for international disarmament, by committing our support to a Nuclear Weapons Convention."

Choices have to be made. We can continue arming ourselves to the teeth, kidding ourselves into playing an imperial role on a stage that we cannot afford, or we can catch up with reality, rid ourselves of nuclear weapons and get behind the push for a nuclear-free world.

There is a huge moral argument against these indiscriminate weapons of mass destruction, but there is also a clear economic case for the resources that they swallow up to be spent on eliminating poverty, ill health and the planet's environmental challenges.

Let the brilliance and skills of the engineers who make these weapons be turned to building for need, not destruction.

Today, commemoration events will be held across the world in memory of the tens of thousands of innocent Japanese whose lives were extinguished by a nuclear whirlwind.

Decades on, the silent vigils in their honour serve as a reminder that the campaign for a world free of nuclear weapons is not a vague dream, but a pressing necessity for the future of humanity.