Pentagon Papers whistle-blower Daniel Ellsberg has told BBC News he was the secret “back-up” for the Wikileaks documents leak, in case something happened to Julian Assange.
This is the first time Mr Ellsberg, who exposed the extent of US involvement in the Vietnam War, has revealed this information.
“I had possession of the all the Chelsea Manning information before it came out in the press,” Mr Ellsberg told BBC Hardtalk’s Stephen Sackur.
Mr Assange’s Wikileaks organisation published more than 700,000 confidential documents, videos and diplomatic cables, provided by the US Army intelligence analyst Chelsea Manning, in 2010.
Mr Ellsberg said Mr Assange “could rely on me to find some way to get it [the information] out”.
The former US military analyst’s 1971 Pentagon Papers leak led to him being dubbed “the most dangerous man in America” by then-US Secretary of State Henry Kissinger.
Mr Ellsberg‘s leak to the New York Times led to a Supreme Court case, as the Richard Nixon administration tried to block the publication.
The government lost that case and the publication of the documents by the New York Times and other news organisations resumed.
Watch the full interview on Monday 5 December on BBC World News and the BBC News Channel.