Over 18 years and through three administrations, both Republican and Democratic, the American people — and most profoundly, American troops — have been lied to about the progress in the war in Afghanistan.

That's the analysis in an unusually blunt assessment from the Office of the Special Inspector General for Afghanistan Reconstruction, a congressionally created agency to investigate waste in the war zone.

The waste may not be surprising considering the nearly $1 trillion U.S. expenditure since the 2001 invasion, which came just weeks after 9/11. But that taxpayer-funded money may actually have backfired because of the corruption it spurred among Afghan government officials, a rot so deep it led many to turn to the Taliban, the al-Qaida sheltering Islamic extremists who were initially routed from power.

Beyond the loss of treasure is the cost in blood. Untold numbers of Afghans have lost their lives in the unending war, as have about 2,300 Americans. An additional 20,589 have been wounded, according to the Pentagon. And not to be forgotten are the sacrifices of many from the NATO nations that came to the aid of their American ally after the U.S. became the first and only county to trigger the collective defense clause known as Article 5.

Congress should begin an immediate, bipartisan investigation into how and why the official characterizations of progress in the conflict continued, and why it took the Washington Post — which broke the story on the report — three years of legal wrangling to get the government to respond to its Freedom of Information Act request.

And while military decisions are ultimately up to the commander-in-chief, Congress should vigorously exercise its oversight role and review Afghan war policy. This includes what the next steps should be for the U.S. and the remaining allies with troops stationed in Afghanistan. While some from both sides of the aisle may reflexively (and understandably, given the gravity of what the Post uncovered) call for an immediate and complete drawdown of U.S. forces, it's crucial that the U.S. not exacerbate its errors with a chaotic withdrawal that would cost even more Afghan and allied lives.

As the Post's admirable reporting revealed, it is years — maybe even a decade — too late to achieve original objectives. But it's not too late to be as strategic as possible when winding down U.S. involvement in this war.