Keep your hands off our secrets says the Pentagon

The Pentagon aimed its appeal primarily at preventing the release of about 15,000 secret documents that the whistleblower website WikiLeaks has said it is holding.

The Pentagon also hopes to stop WikiLeaks from making public the contents of a mammoth encrypted file recently added to the site.

Contents of that file remain a mystery.

Pentagon spokesman Geoff Morrell said: "We are asking them to do the right thing. I don't know that we're very confident they'll have a change of heart."

WikiLeaks did not immediately reply to calls and emails seeking comment on the Pentagon's demand, although on its Twitter feed the group seemed dismissive, calling Mr Morrell "obnoxious" and saying his demand was tantamount to a "formal threat".

WikiLeaks posted more than 76,900 classified military and other documents, mostly raw intelligence reports from Afghanistan, on its website on July 25. The 15,000 additional documents are apparently related to that material.

The documents leaked so far illustrate the frustration of US forces in fighting the protracted Afghan conflict and revived debate over the war's uncertain progress. The White House angrily condemned the leaks, saying they put the lives of Afghan informants and US troops at risk.

"The Defence Department demands that WikiLeaks return immediately to the US government all versions of documents obtained directly or indirectly from the Department of Defence databases or records," Mr Morrell said.

He called the material stolen property, but would not say whether the demand was a prelude to legal action against the website or others.

Mr Morrell spoke at a Pentagon press conference that amounted to a televised public appeal to the secretive site and its editor in chief, Julian Assange.

Generally speaking, WikiLeaks has so far struck an uncompromising tone. Mr Assange, speaking in London last week, said that he had no obligation to the US military and found the very notion of "national security" ridiculous.

US Army private Bradley Manning is custody on suspicion of leaking classified material to WikiLeaks in a previous case. He was a "person of interest" in the latest release, Mr Morrell said.

It remains highly unlikely that the Pentagon can recapture all electronic forms of the documents already placed online and since downloaded and examined by countless people.

"The genie is out of the bottle," Mr Morrell said.

The Pentagon has had no direct contact with WikiLeaks about possible efforts to withhold some information in the documents to make them less of a security threat, he said, and he ruled out such an exercise.

"We're not looking to have a conversation about harm minimisation," Mr Morrell said. "We're looking to have a conversation about how to get these perilous documents off the website as soon as possible, return them to their rightful owners and expunge them from their records."

The Pentagon had some idea what the 15,000 unpublished documents contain, he said.