Hundreds of confidential interviews with key figures involved in prosecuting the 18-year US war in Afghanistan have revealed that the US public has been consistently misled about an unwinnable conflict.

Transcripts of the interviews, published by the Washington Post after a three-year legal battle, were collected for a Lessons Learned project by the Office of the Special Inspector General for Afghanistan Reconstruction (Sigar), a federal agency whose main task is eliminating corruption and inefficiency in the US war effort.

The 2,000 pages of documents reveal the bleak and unvarnished views of many insiders in a war that has cost $1tn (£760bn) and killed more than 2,300 US servicemen and women, with more than 20,000 injured. Tens of thousands of Afghan civilians have died in the conflict.

The documents have echoes of the Pentagon Papers – the US military’s secret history of the Vietnam war that were leaked in 1971 and told a similarly troubling story of the cover-up of military failure.

Negotiations are taking place between the Trump administration and the Taliban as the US debates whether to withdraw 13,000 troops who remain in Afghanistan.

The interviews were collected, beginning in 2014, in addition to Sigar’s regular audits to identify what could be learned from successive policy failures in Afghanistan.

While many of the failures of the war in Afghanistan have been exposed by Sigar’s work, often in highly technical reports, the cache of interviews offers an easily accessible fly-on-the-wall account.

In his own damning intervention John Sopko, the head of Sigar, told the paper the assessments contained in the project suggested that “the American people have constantly been lied to”.

Two major claims in the documents are that US officials manipulated statistics to suggest to the American public that the war was being won and that successive administrations turned a blind eye to widespread corruption among Afghan officials, allowing the theft of US aid with impunity.

The long-term nature of the manipulation of statistics was detailed in an interview with an individual identified only as a senior “National Security Council official”.

“It was impossible to create good metrics. We tried using troop numbers trained, violence levels, control of territory and none of it painted an accurate picture,” the official told interviewers in 2016. “The metrics were always manipulated for the duration of the war.”

The papers depict the view of many people of a conflict with vague and unachievable war aims, pursued under three US presidents, George W Bush, Barack Obama and Donald Trump, whose alleged successes were presented repeatedly in inflated terms.

In one scathing assessment Douglas Lute, a lieutenant general who served as the White House Afghan war tsar during the George W Bush and Barack Obama administrations, told interviewers in 2015: “We were devoid of a fundamental understanding of Afghanistan – we didn’t know what we were doing.”

Speaking frankly, like other interviewees, on the understanding that what he was saying at the time was confidential, he added: “What are we trying to do here? We didn’t have the foggiest notion of what we were undertaking.

“If the American people knew the magnitude of this dysfunction … 2,400 lives lost.”

In another interview Jeffrey Eggers, a retired Navy Seal and White House staffer for Bush and Obama, said: “What did we get for this $1tn effort? Was it worth $1tn?

“After the killing of Osama bin Laden, I said that Osama was probably laughing in his watery grave considering how much we have spent on Afghanistan.”

Some of those interviewed by the Sigar project went even further, suggesting a deliberate effort to alter statistics on the war to suggest to the American public that it was being won.

“Every data point was altered to present the best picture possible,” said Bob Crowley, an army colonel who served as a senior counterinsurgency adviser to US military commanders in 2013 and 2014.

“Surveys, for instance, were totally unreliable but reinforced that everything we were doing was right and we became a self-licking ice-cream cone.”

The documents, obtained after the Washington Post twice went to federal courts to ask for the interview transcripts, identify only 62 of the people interviewed. A total of 366 other names were redacted after Sigar insisted they should be treated as whistleblowers and informants.

Commentators and foreign policy experts were quick to point to the importance of the documents, with many drawing a link with the Pentagon Papers.

The veteran US documentary-maker Ken Burns, who recently chronicled the Vietnam War, remarked on Twitter: “Mark Twain often said that ‘history doesn’t repeat itself but it often rhymes.’ ‘The Afghanistan Papers’ and ‘The Pentagon Papers’ certainly rhyme in that sense.”

Mark Twain often said that "history doesn't repeat itself but it often rhymes."



"The Afghanistan Papers" and "The Pentagon Papers" certainly rhyme in that sense.



Incredible reporting by @CraigMWhitlock of @washingtonpost.https://t.co/XCbErrYBxo https://t.co/Z7eHerNE6H — Ken Burns (@KenBurns) December 9, 2019

The NPR host Lulu Garcia-Navarro tweeted: “Stunning. The new Pentagon Papers describe explicit and sustained efforts by the US government to deliberately mislead the public.”.

Stunning. The new Pentagon papers describe ‘ explicit and sustained efforts by the U.S. government to deliberately mislead the public...to distort statistics to make it appear the United States was winning the war when that was not the case.’ https://t.co/uAFTRXgNUj — Lulu Garcia-Navarro (@lourdesgnavarro) December 9, 2019

Some were even more succinct. “Wars breed lies,” tweeted Katrina vanden Heuvel, the publisher of the progressive magazine the Nation.