Daniel Ellsberg, who leaked classified documents around the Vietnam War known as the Pentagon Papers, has died at 92.

Mr Ellsberg, who had been diagnosed with inoperable pancreatic cancer in February, died at his home in California, his family said.

Long before WikiLeaks or Edward Snowden, the Pentagon Papers were one of the most famous leaks in history, a case fictionalised in the 2017 Steven Spielberg movie The Post.

The documents revealed long-time US government doubts and deceit about the Vietnam War and sparked a furious reaction by then US president Richard Nixon.

The military analyst became the target of a smear campaign by the White House, with the president’s national security adviser, Henry Kissinger, calling Mr Ellsberg “the most dangerous man in America who must be stopped at all costs”.

Mr Ellsberg, a Harvard graduate, was a long well-placed member of the government-military elite. He had been an early supporter of the Vietnam War – but changed his mind, and went on to denounce it publicly.

Then, he secretly went to the media in 1971 in hopes of expediting the end of the yearslong conflict.

The Pentagon Papers had been commissioned by then defense secretary Robert McNamara in 1967 – and Pentagon officials had secretly been putting together a 7,000-page report covering US involvement in Vietnam from 1945 through 1967.

They were leaked and first published in The New York Times in June 1971.

The leaker’s identity became a national guessing game.

The Times never said who leaked the papers, but Mr Ellsberg was an obvious suspect because of his access to the papers and his public condemnation of the war over the previous two years.

With the FBI in pursuit, he turned himself in to authorities in Boston – becoming a hero to the anti-war movement and a traitor to the war’s supporters.

The Nixon administration quickly tried to block further publication on the grounds that the papers would compromise national security, but the US Supreme Court ruled in favour of the newspapers in a landmark case in 1971.

In his latter years, Mr Ellsberg became an advocate for government transparency.

He said Mr Snowden, a contractor for the National Security Agency who gave journalists thousands of classified documents on government information-gathering, had done nothing wrong.

He also said he considered Army Private Chelsea Manning a hero for turning over a trove of government files to WikiLeaks.