On 26 July, WikiLeaks released thousands of secret US military files on the war in Afghanistan. Cover-ups, a secret assassination unit and the killing of civilians are documented. In file after file, the brutalities echo the colonial past. From Malaya and Vietnam to Bloody Sunday and Basra, little has changed. The difference is that today there is an extraordinary way of knowing how faraway societies are routinely ravaged in our name. WikiLeaks has acquired records of six years of civilian killing in both Afghanistan and Iraq, of which those published in the Guardian are a fraction.

There is understandably hysteria on high, with demands that the WikiLeaks founder, Julian Assange, be "hunted down" and "rendered". In Washington, I interviewed a senior official in the defence department and asked: "Can you give a guarantee that the editors of WikiLeaks and the editor-in-chief, who is not American, will not be subjected to the kind of manhunt that we read about in the media?" He replied: "It's not my position to give guarantees on anything."

He referred me to the "ongoing criminal investigation" of a US soldier, Bradley Manning, an alleged whistleblower. In a nation that claims its constitution protects truth-tellers, the Obama administration is pursuing and prosecuting more whistleblowers than any of its modern predecessors. A Pentagon document states bluntly that US intelligence intends to "fatally marginalise" WikiLeaks. The preferred tactic is smear, with corporate journalists ever ready to play their part.

The Pentagon line

On 31 July, the American celebrity reporter Christiane Amanpour interviewed the US secretary of defence, Robert Gates, on the ABC network. She invited him to describe to her viewers his "anger" at WikiLeaks. She echoed the Pentagon line that "this leak has blood on its hands", cueing Gates to find WikiLeaks "guilty" of "moral culpability". Such hypocrisy coming from a regime drenched in the blood of the people of Afghanistan and Iraq - as its own files make clear - is apparently not for journalistic inquiry. This is hardly surprising now that a new and fearless form of public accountability, which WikiLeaks represents, threatens not only the warmakers but also their apologists.

Their current propaganda is that WikiLeaks is "irresponsible". Earlier this year, before it released the cockpit video of a US Apache gunship killing 19 civilians in Iraq, including journalists and children, WikiLeaks sent people to Baghdad to find the victims' families in order to prepare them. Before the release of last month's Afghanistan war logs, WikiLeaks wrote to the White House asking that it identify Afghan names that might draw reprisals. There was no reply. More than 15,000 files were withheld and these, Assange says, will not be released until they have been scrutinised "line by line" so that the names of those at risk can be deleted.

The pressure on Assange himself seems unrelenting. In his homeland, Australia, the shadow foreign minister, Julie Bishop, has said that if her right-wing coalition wins the general election on 21 August, "appropriate action" will be taken "if an Australian citizen has deliberately undertaken an activity that could put at risk the lives of Australian forces in Afghanistan or undermine our operations in any way". The Australian role in Afghanistan, which is in effect mercenary to Washington, has produced two striking results: the massacre of five children at a village in Uruzgan Province and the overwhelming disapproval of the majority of Australians.

Last May, following the release of the Apache footage, Assange had his passport temporarily confiscated when he returned home. The Labor government in Canberra denies it has received requests from Washington to detain him and spy on the WikiLeaks network. The Cameron government also denies this. They would, wouldn't they? Assange, who came to London last month to work on exposing the war logs, has now had to leave the country hastily for, as he puts it, "safer climes".

A duty to publish

On 16 August, the Guardian, citing Daniel Ellsberg, described the great Israeli whistleblower Mordechai Vanunu as "the pre-eminent hero

of the nuclear age". Vanunu, who alerted the world to Israel's secret nuclear weapons, was kidnapped by the Israelis and incarcerated for 18 years after he was left unprotected by the Sunday Times, which had published the documents he supplied. In 1983, another heroic whistleblower, Sarah Tisdall, a Foreign Office clerical officer, sent documents to the Guardian disclosing how the Thatcher government planned to spin the arrival of US cruise missiles in Britain. The Guardian complied with a court order to hand over the documents, and Tisdall went to prison.

The WikiLeaks revelations shame the dominant section of journalism, devoted merely to taking down what cynical and malign power tells it. This is state stenography, not journalism. Look on the WikiLeaks site and read a Ministry of Defence document that describes the "threat" of real journalism. And so it should be a threat. Having skilfully published the WikiLeaks exposé of a fraudulent war, the Guardian should now give its most powerful and unreserved editorial support to the protection of Assange and his colleagues, whose truth-telling is as important as any in my lifetime.

I like Julian Assange's dust-dry wit. When I asked him if it was more difficult to publish information in Britain, with its draconian secrecy laws, he replied: "We haven't found a problem. When we look at Official Secrets Act labelled documents, we see that they state it is an offence to retain the information and an offence to destroy the information. So the only possible outcome is to publish the information."