Washington, June 16 (RHC)-- Daniel Ellsberg, a whistleblower famed for exposing government deception over the United States’s war in Vietnam and an outspoken opponent of nuclear weapons, has died at the age of 92 from pancreatic cancer.  The Washington Post was the first to report that Ellsberg died on Friday, citing a statement from his family.

While Ellsberg was best known for his efforts to bring a trove of secret documents known as “the Pentagon Papers” to public attention, he remained actively engaged in activism on a number of issues, such as protection for whistleblowers and the dangers of nuclear weapons, until the end of his life.

At the time of the Pentagon Papers leak, Henry Kissinger, an architect of U.S. escalation of the Vietnam War and then national security adviser to former President Richard Nixon, called Ellsberg “the most dangerous man in America who must be stopped at all costs.”

Ellsberg had worked as a military analyst on national security issues for the Pentagon and the RAND Corporation, a prominent policy think tank, before becoming disillusioned with the US war in Vietnam and leaking thousands of pages of documents detailing government lies about the war to the media in 1971.

The episode resulted in a landmark battle over freedom of speech that made its way to the US Supreme Court. Less than two weeks after the papers were published, the court ruled that the press had the right to publish the materials leaked by Ellsberg, a crucial victory for efforts to expose government falsehoods on issues such as national security.

The US government charged him in January 1973 with theft and conspiracy under the Espionage Act, facing a maximum of 115 years in prison.  The charges were dismissed in May of that year because of government misconduct and illegal evidence gathering.

Throughout his life, Ellsberg railed against the use of the Espionage Act and remained a fierce advocate for the rights of whistleblowers such as Edward Snowden and Julian Assange, both of whom released classified documents to the public revealing government abuses such as illegal mass surveillance and the killing of civilians in US wars overseas.

In a 2014 interview with Al Jazeera, Ellsberg spoke about the dangers of widespread classification of government documents and a “culture of secrecy” in the US national security apparatus.