U.S. commanders sometimes refers to the dunderheads who make these mistakes as “strategic corporals” — meaning that a blunder by a low-ranking soldier can affect the strategic stakes in a campaign involving more than 100,000 U.S. troops and something approaching $1 trillion in spending. And that seems to have happened here.

Gen. John Allen, who commands U.S. forces in Afghanistan, issued a hyper-apologetic statement today after several thousand protesters gathered outside the huge Bagram base. He confirmed that NATO forces at Bagram “improperly disposed of a large number of Islamic religious materials which included Korans. When we learned of these actions, we immediately intervened and stopped them. . . . I promise you, this was NOT intentional in any way.”

Allen is a smart general, and he knows better than anyone the limited value of these mea culpas and promises to investigate. They’re like the apologies made after the release in January of a cell-phone video showing U.S. troops urinating on the corpses of Taliban fighters. People remember the appalling images, but forget the statements explaining how rare and unintentional these actions are.

What’s disturbing about this incident is that Afghans had to stop the strategic corporals (ie, dunderheads) in the apparent act of desecration. The New York Times quotes an Afghan worker named Abdul Wahid: “American soldiers brought a pickup truck loaded with new copies of the Koran in its trunk and dropped it in burning pitch.”  The Afghan said he and two friends intervened and told the soldiers they would give the Korans to local mullahs for proper disposal.

Friends who recall the horrors of Vietnam remind me that soldiers do dumb things, and sometimes cruel things, because of the corrosive and exhausting nature of war. But in a counterinsurgency campaign like Afghanistan, such errors are immensely costly to the mission of stabilizing the country under U.S.-backed local forces. Enough little mistakes like this, and the larger battle becomes unwinnable.

The Bagram incident is a good reminder why it’s sound policy to move U.S. troops out of their lead combat role next year and shift responsibility for security to Afghan forces. But it boggles the mind that 10 years into this war, some idiot could back up a truck to a fire and prepare to torch the text held sacred by the people we say we are there to help.