US defence secretary Leon Panetta has apologised for gruesome, newly revealed photographs that show US soldiers posing with the bloodied remains of dead insurgents in Afghanistan.
He said war can lead young troops to "foolish decisions" and expressed concern the photos could incite fresh violence against Americans.
The White House called the two-year-old photos "reprehensible", joining Mr Panetta and other top military officials in expressing regret for the latest in a string of embarrassing missteps by the US military in a war that is built on earning the trust and confidence of ordinary Afghans.
In recent months, American troops have been caught up in controversies over burning Muslim holy books, urinating on Afghan corpses, an alleged massacre of 17 Afghan villagers and other misdeeds.
"This is war. I know that war is ugly and it's violent, and I know that young people sometimes caught up in the moment make some very foolish decisions," Mr Panetta said. "I am not excusing that behaviour, but neither do I want these images to bring further injury to our people or to our relationship with the Afghan people.
"My apology is on behalf of the Department of Defence and the US government," Mr Panetta told a news conference in Brussels following a meeting of Nato allies at which the way ahead in Afghanistan was the central topic.
The photos were published in Wednesday's Los Angeles Times. One shows members of the 82nd Airborne Division posing in 2010 with Afghan police holding the severed legs of a suicide bomber.
The same platoon a few months later was sent to investigate the remains of three insurgents reported to have accidentally blown themselves up - and soldiers again posed for a photo with the remains, the newspaper said. A photo from the second incident appears to show the hand of a dead insurgent resting on a US soldier's shoulder as the soldier smiles.
Mr Panetta said he had urged the newspaper not to publish the photos, which it said it were given by a member of the 82nd Airborne.
"The reason for that is those kinds of photos are used by the enemy to incite violence, and lives have been lost by the publication of similar photos in the past," he said in Brussels.