Daniel Ellsberg: The 90-year-old whistleblower tempting prosecution
Known as the Pentagon Papers, the documents were part of a classified study that showed the extent of American involvement in the Vietnam War.
At the same time, Mr Ellsberg copied another classified study that showed how seriously American military chiefs took the threat of nuclear war during the Taiwan crisis of 1958.
For 50 years, the study went virtually unnoticed until 2017, when Mr Ellsberg published the full document online, which was highlighted by the New York Times newspaper last month.
In theory, Mr Ellsberg's disclosure could put him at risk of prosecution on the same charges he faced for leaking the Pentagon Papers.
Now aged 90, Mr Ellsberg says he is not intimidated by the possibility of prison. In an interview with the BBC, he explained why.
For decades, Mr Ellsberg has been a tireless critic of government overreach and military interventions. His opposition crystallised during the 1960s, when he advised the White House on nuclear strategy and assessed the Vietnam War for the Department of Defense.
