London:
WikiLeaks' editor-in-chief claims his organization doesn't know who sent it some 91,000 secret US military documents, telling journalists that the website was set up to hide the source of its data from those who receive it.
Julian Assange didn't say whether he meant that he had no idea who leaked the documents, or whether his organization simply could not be sure. But he did say the added layer of secrecy helped protect the site's sources from spy agencies and hostile corporations.
"We never the know the source of the leak," he told journalists gathered at London's Frontline Club late Tuesday. "Our whole system is designed such that we don't have to keep that secret."
While Assange acknowledged that the site's anonymous submissions raised concerns about authenticity, he said WikiLeaks had yet to be fooled by a bogus document.
"We do see wholly fabricated submissions, usually around election time," he said, but added that they were "quite rare."
Operatives inside Afghanistan and Pakistan who have worked for the US against the Taliban or Al-Qaida may be at risk following the disclosure of thousands of classified US military documents, former and current US officials said.
Speaking in Washington on Tuesday, President Barack Obama said he was concerned about the massive leak of sensitive documents about the Afghanistan war, but that the papers did not reveal any concerns that were not already part of the debate.
In his first public comments on the matter, Obama said the disclosure of classified information from the battlefield "could potentially jeopardize individuals or operations."
As the Obama administration scrambles to repair any political damage to the war effort in Congress and among the American public by the WikiLeaks revelations, there are also growing concerns that some US allies abroad may ask whether they can trust America to keep secrets.
In Baghdad, Adm Mike Mullen, chairman of the Joint Chiefs of Staff, told reporters he was "appalled" by the leak. He said "there is a real potential threat there to put American lives at risk."
US Attorney General Eric Holder said he "deplores" the leak of Afghan war secrets and an investigation by the Pentagon and Justice Department will determine whether criminal charges will be filed.
Holder, speaking to reporters during a visit to Egypt on Wednesday, says the investigation aimed to determine the source of the leak. He says "whether there will be criminal charges brought will depend on how the investigation goes."
The Army is leading the Pentagon's inquiry into the source of the leak.
In London, Assange said WikiLeaks had ex-military and former intelligence workers "in our network," people he said could help evaluate whether documents leaked from the armed forces or spy agencies were genuine.
The website's worse fear, he said, was not a complete forgery but a real document that had been subtly tampered with. Still, he said he had yet to see that happen.
Assange spoke for nearly two-and-a-half hours, outlining his site's mission and methods, and defending it from criticisms that it had put lives at risk by putting mountains of classified information in the public domain.
He seemed irritated when one member of the audience asked him whether he believed there were ever any legitimate national security concerns that would prevent him from publishing a leaked document.
"You often hear ... that something may be a threat to US national security. This must be shot down, whenever this statement is made. A threat to US national security? Is anyone serious? The security of the entire nation of the United States? It is ridiculous!" he declared.
But he admitted that individual cases were different.
"If we are talking a threat to individual soldiers ... or citizens of the United States, then that is potentially a genuine concern," he said.