Wikileaks has published more than 1.7 million US diplomatic and intelligence reports from the 1970s.
They include allegations that former Indian PM Rajiv Gandhi was a middleman in an arms deal and the first impressions of eventual British PM Margaret Thatcher.
The documents have not been leaked and are available to view at the US national archives. Wikileaks says it is releasing the documents in searchable form.
Much of the work has been carried out by the website's founder Julian Assange while he has been holed up at the Ecuadorean embassy in London.
Mr Assange took refuge in the embassy last June to avoid extradition to Sweden, where he is wanted for questioning over allegations that he sexually assaulted two female ex-Wikileaks supporters in 2010.
He denies the allegations, and has said they are politically motivated and part of a smear campaign against him and his whistle-blowing website.