A witness to any crime has responsibilities that are essential to maintaining a civilised society. The first responsibility is to the victim, to offer whatever help is possible. The second is to help bring the offender to justice. Australia, as a result of its intelligence gathering, has emerged as a key witness to crimes against humanity. Material provided to The Age this week confirms that the Australian Government is uniquely able to provide evidence against those in the Indonesian military and government who oversaw the violence inflicted on East Timor before and after its people voted for independence on August30, 1999. That the orders came from high up is clear from the sheer magnitude of what happened: the terrorising of an entire population and murder of up to 2000 people; the forced removal of 250,000 to West Timor; the razing of most infrastructure. All the while, Australian eyes and ears, using advanced monitoring equipment, watched and listened. They heard Indonesian generals direct and conspire with militia leaders. They saw high-resolution images, capable of identifying individuals. Everything was systematically recorded: identities, chains of command, dates and times. The guilty parties went to great lengths to cover their tracks in East Timor, but they could not destroy the secret evidence that the Defence Signals Directorate now holds in Canberra.

More than two years later, however, Australia remains a silent witness. The government has shared little of what it knows with any court (two are sitting, one in Indonesia and one in East Timor). This week a special court in Jakarta began trying 18 suspects, but the big fish – many of whom still occupy positions of power - appear to have slipped through the net. Tellingly, Indonesia has repudiated a 2000 agreement to honour United Nations extradition requests. Australia co-sponsored the 1999 resolution that set up the UN investigations that could yet lead to a UN war crimes tribunal. In the same year, Foreign Minister Alexander Downer said Australia would "obviously assist with the UN inquiry" and would take into account precedents such as in Rwanda and the Balkans. Last July, he welcomed the prosecution of former Yugoslav president Slobodan Milosevic. A crucial factor in that case was that the US and Britain supplied intelligence material.

Australia has a moral obligation to follow suit. Doing so would not only help bring crimes to court, but would deliver a warning to regimes that even now are committing or contemplating atrocities: they will be called to account. Canberra may have concerns about compromising its intelligence gathering and its ties with Jakarta, but a crime against humanity, by definition, is a crime against us all, which transcends issues of politics or sovereignty. When justice was compromised in the past, from Nazi Germany through to Cambodia, the decisions came back to haunt us. Indeed, the release of the DSD documents reflects disquiet within the defence community about this nation's present culpability. Ironically, Australia and Indonesia recently agreed to share intelligence to combat terrorism. In the defence of civilisation, how Australia responds to crimes against humanity is no less significant.