The paper obtained the 2,000 pages of documents — including what it says are notes from more than 400 interviews with military commanders, diplomats and aid workers, as well as Afghan officials, that were part of a “lessons learned” project — after a three-year legal battle. The Post also said it obtained hundreds of memos by former Secretary of Defense Donald Rumsfeld.

NBC News has not been able to independently review the documents.

The Pentagon disputed it has been misleading about Afghanistan and insisted it has been as transparent as possible regarding the war.

"There has been no intent by DoD to mislead Congress or the public," Col. Thomas Campbell, defense department spokesperson, said in a statement to NBC News. "DoD officials have consistently briefed the progress and challenges associated with our efforts in Afghanistan, and DoD provides regular reports to Congress that highlight these challenges."

The White House and the State Department did not immediately respond to requests for comment.

The Post published the documents two days after U.S.-Taliban talks restarted, and compared them to the Pentagon Papers — a top-secret government study that was packed with damaging revelations about America’s conduct in the Vietnam War leaked to The New York Times and the Post in 1971.

The war in Afghanistan is America’s longest and has raged on for 18 years. America has had boots on the ground there since 2001, when U.S. forces toppled the Taliban regime for harboring Osama bin Laden, the architect behind the Sept. 11, 2001 terror attacks.

Since then, just under 2,300 American troops have died in the war-torn country. Between January 2009, when the United Nations began a systematic documentation of civilian casualties, and September this year, some 34,000 Afghan civilians died as a result of the armed conflict.

The head of the federal agency that conducted the interviews, John Sopko, declined to comment to NBC News in advance of the report's publication. But Sopko told the Post that the documents show “the American people have constantly been lied to.”

In one of the reported interviews, Army Col. Bob Crowley, who served as a senior counterinsurgency adviser to U.S. military commanders in 2013 and 2014, told government interviewers in 2016 that “every data point was altered to present the best picture possible.”