In May last year, US Army private Bradley Manning, under arrest and charged with being the source of the biggest public leak of classified information in US history, allegedly told FBI informant Adrian Lamo: ''Hilary Clinton, and several thousand diplomats around the world, are going to have a heart attack when they wake up one morning and find an entire repository of classified foreign policy is available, in searchable format to the public.''

Whatever Manning's ultimate responsibility for the leaks, the outcome he allegedly predicted has come to be.

Having decided last Friday to put the whole ''cablegate'' database on its website, WikiLeaks has delivered an astonishingly comprehensive, publicly available, fully searchable and free archive of US diplomacy covering every corner of the globe. The archive mostly covers the past five years, although some records date back further. There are no redactions or deletions.

The cables show the inner workings of diplomacy and politics in every country in the world. They show how the US as a global power defines, pursues and defends its interests - diplomatic, military, commercial and ideological - sometimes for good and sometimes at considerable cost to other countries, communities and individuals.

This immense collection of material, the product of the largest and best resourced diplomatic service in the world, is a unique and extraordinarily accessible resource for journalists, political activists, human rights workers, academic researchers, and indeed ordinary members of the public around the world.

And once again WikiLeaks and Assange are back in the headlines. It's a characteristically controversial turnaround for the organisation, which for some months looked as if it was drifting into the doldrums.

Beginning in late November last year, WikiLeaks and its initial group of media partners - The Guardian, The New York Times, Le Monde, Der Spiegel and El Pais - embarked upon the largest and most dramatic publication of classified government information since the US Pentagon papers were leaked three decades earlier.

A little more than a week later, Fairfax also began the publication in Australia of a series of front page stories based on the leaked cables of the US embassy in Canberra - provided by WikiLeaks - that shed new light on the workings of the federal Labor government and Australia's relations with our most important ally.

There was a huge surge of media and public interest, not only in the US embassy cables, but also in WikiLeaks and Assange himself.

The WikiLeaks founder was dramatically arrested in Britain on a European extradition warrant to face questioning by Swedish prosecutors in relation to an allegation of sexual molestation.

Assange was briefly imprisoned before being bailed pending further legal proceedings and subjected to a highly restrictive form of house arrest at WikiLeaks' headquarters at Ellingham Hall in rural Norfolk. He remains there, now in his 274th day of detention, awaiting the outcome of an appeal before Britain's High Court.

However, while reports based on the leaked US cables continued to be published as WikiLeaks formed new partnerships with dozens of media organisations around the globe, the mainstream Western media caravan largely moved on.

In a media environment often focused more on novelty than substance, WikiLeaks and the US embassy cables became old hat for many media outlets - though not for Fairfax, which continued to publish a steady stream of revelations covering such topics as Australian federal politics, the inner thinking of BHP chief executive Marius Kloppers, and Indonesia, China, Japan, Singapore, Fiji, Papua New Guinea and elsewhere in the Asia-Pacific region.

When I visited Assange at Ellingham Hall earlier this year, the atmosphere was very different from when I travelled there last November and first secured access to the US embassy cables. Then WikiLeaks' hastily organised headquarters was abuzz with activity as Assange and his team prepared for the initial cablegate releases.

This time all was quiet. The pace of business had slackened considerably and we spent most of a leisurely afternoon in the kitchen, chatting without interruption as we nibbled cheese and sipped an Australian merlot.

At that time, and in my earlier discussions with him last November, Assange left me with little doubt that his personal preference was for complete or near complete openness; that in an ideal world all the US embassy cables should be released in full without fear or favour.

He was certainly sceptical about US government claims that the release of the cables would endanger the lives of confidential sources of information. In the case of the US Army's Afghanistan and Iraq war diaries, released by WikiLeaks earlier in 2010, there had been much huffing and puffing from the Pentagon, but no instances of actual harm had been identified.

Moreover, in the US embassy cables many of the ''protected'' confidential diplomatic sources were in fact politicians, senior officials and business figures who had chosen for their own purposes to talk privately with American diplomats, so WikiLeaks was under no obligation to protect their interests.

On the contrary, there appeared to be a strong public interest in exposing what were often undeclared, indeed publicly denied, links between political players around the globe and the world's one global power.

Assange nonetheless felt duty bound to adhere to the process of slowly vetting the cables, with WikiLeaks either making its own judgments or drawing on advice from its media partners to identify sensitive information and recommend redactions and deletions from the published texts.

That has now all changed following the dramatic disclosure last week that the entire US cables database could be found on the internet in an encrypted file that could be opened with a password published in a book by Guardian journalists David Leigh and Luke Harding.

Who is responsible for this extraordinary security lapse is hotly disputed between Assange and The Guardian.

But having witnessed The Guardian's dealings with WikiLeaks at a meeting in London last November, I was appalled at the newspaper's treatment of the group that delivered it such an astonishing bounty of information. The personal contempt of senior Guardian journalists for Assange - whom one referred to as ''a source, nothing more'' - was all too clear.

Against that background, I found it unsurprising that The Guardian ignored Assange's most basic security instructions - never reveal the key to encrypted material that is or has been, however fleetingly, publicly available - and it must bear ultimate responsibility for the leak of the entire unredacted database.

In these circumstances, Assange's decision last Friday to publish the US cable archives on the WikiLeaks website may well have conformed with his personal inclinations, but it was also entirely justified.

Thanks to The Guardian, the horse had bolted, not merely into the next paddock but around the globe.

Assange set out his reasoning in media interviews this week: it was a simple fact that the cables were already circulating widely online after their location and the link with the published password had been identified and disseminated, allegedly by former WikiLeaks member Daniel Domscheit-Berg.

''Let us look at this case properly,'' Assange said, ''The Guardian newspaper revealed the entire encryption password including that component they were instructed never to write about, and did so in breach of their contract.''

After that ''a race commenced between the governments who need to be reformed and the people who can reform them using the material.

''By the time we published the cables, the material was already on dozens of websites … and [was] being tweeted everywhere. And even a searchable public interface had been put up on one of them.

''We had a case where every intelligence agency has the material and the people who are mentioned do not have the material … So you have a race between the bad guys and the good guys and it was necessary for us to stand on the side of the good guys,'' Assange said.

Another motive for WikiLeaks publishing the entire archive, Assange argued, was the need for an authoritative source for leaked material.

Although versions of the leaked US cables were appearing online, ''there was not an authorised version of the cables that the public could rely on. By 'authorised' I mean a version that is known to be true - it doesn't have another agenda.

''The unauthorised versions that were being tweeted everywhere - although as far as we can determine they were accurate, the public and journalists couldn't know they were accurate.''

All things considered, Assange's position is a defensible one. However, as someone who has had direct and extended access to a significant portion of the US cables archive, I have no doubt the potential for harm is still great.

The danger arises not in countries like Australia, where the revelation that Labor senator Mark Arbib has been a valued source for the US embassy brought embarrassment and criticism, but nothing more.

It is a very different matter in countries such as China, where the arbitrary exercise of state power is very real and the disclosure of even quite innocuous information can be declared a breach of state secrecy or even espionage.

For example, secret and confidential cables from the US embassy in Beijing and other US diplomatic posts in China contain hundreds of reports of off-the-record and sometimes extremely sensitive conversations with Chinese officials, academics, business people, human rights activists, political dissenters and, indeed, ordinary people.

These disclosures range from academics who have revealed their knowledge of internal Chinese Communist Politburo politics, to officials who have revealed corruption and maladministration, to lawyers who have reported breaches of human rights.

In the case of China, the caveat in the cables to ''please protect'' carries very real significance. This doesn't mean that the Chinese Ministry of State Security will round up all the US diplomats' contacts next week. That is unlikely. But many of these people will now be at risk.

THE same risks apply in numerous other countries with authoritarian regimes and active state security services. In the end the casualties of openness may not be great, but for some individuals the consequences may be severe.

In the short term, however, the most immediate effect is another dramatic surge in global media interest in the US embassy cables, WikiLeaks and Julian Assange.

WikiLeaks, through its Twitter feed, claims that it has helped create more than 30,000 new stories worldwide in the past week, with a new news article appearing every two minutes.

However, WikiLeaks' future is uncertain. Assange will get a decision on his extradition appeal next month. Indeed, his extremely expensive legal problems are unlikely to end any time soon.

He may yet be extradited to Sweden and the possibility remains of eventual extradition to the United States, where prosecutors are leading a secret grand jury panel in a covert investigation of possible espionage charges against WikiLeaks members.

Assange's British visa has reportedly expired. So if he wins his court appeal, he may be coming home to Australia, where he is unlikely to face any criminal charges arising from the publication of the name of a senior ASIO officer in one US embassy cable.

However, as federal Attorney-General Robert McClelland's resumption of verbal hostilities confirmed last week, the federal government has no sympathy for Assange and may go out of its way to make his life uncomfortable.

But more seriously, nearly a year after critical software was removed by Domscheit-Berg and another WikiLeaks defector, WikiLeaks' confidential submission mechanism remains out of action.

Assange says the facility will be up and running soon and that WikiLeaks has more startling information in its secure servers, but this remains to be seen.

His trajectory may prove to be like that of a skyrocket, emitting ever larger explosions and showers of sparks before inevitably falling to earth. There will probably be some more bangs, but whether they will be anything as dramatic as those of the past year is unclear.

Meanwhile, however, Assange has had a greater impact on the global political landscape than any other Australian in recent decades. No one can deny him that.