The U.S. military once again condemned the actions of some of its troops in Afghanistan on Wednesday after photographs surfaced of smiling soldiers posing with dead insurgents in the latest battlefield scandal.

The photographs, obtained by the Los Angeles Times, show soldiers posing next to Afghan corpses, including the mangled body of a suicide bomber hoisted by his ankles. In another shot, which the newspaper described but did not publish, two soldiers hold up a dead man’s hand, extending his middle finger.

The 18 photographs were taken in 2010 in Zabul province by soldiers from the 82nd Airborne’s 4th Brigade Combat Team, the newspaper reported. Although the pictures were dated, the fresh disclosure of misconduct extends a string of recent incidents in which U.S. troops have disrespected the dead, allegedly killed Afghan civilians and desecrated the Quran.

U.S. officials, concerned that the cumulative effect will further alienate an Afghan public, disavowed the actions depicted in the photos and said they had already launched investigations.

In Brussels, where NATO ministers were meeting to discuss the war’s progress, Defense Secretary Leon Panetta apologized. He said he “strongly condemned” the soldiers’ actions but portrayed them as immature reactions to battlefield stress.

“This is war, and I know war is ugly, and is violent,” Panetta said. “I know young people sometimes caught up in the moment make some very foolish decisions.

“I am not excusing that behavior,” he added.

The photographs mark the latest public relations setback for the U.S. military as it seeks to gradually withdraw from Afghanistan.

In January, an Internet video showed Marines laughing as they urinated on the corpses of three insurgent fighters. In February, riots erupted after U.S. soldiers inadvertently incinerated copies of the Quran. In March, an Army staff sergeant was charged with killing 17 Afghan villagers, mostly women and children, in Kandahar province.

Meantime, distrust is building between U.S. forces and their Afghan allies. The number of treacherous, lethal attacks by uniformed Afghan security forces against NATO troops and trainers has risen substantially this year.

In addition to condemning the actions depicted in the latest batch of battlefield photographs, the Pentagon criticized the Los Angeles Times for publishing them.

Panetta said defense officials had urged the Times to suppress the pictures. George Little, the Pentagon press secretary, suggested the newspaper’s decision could put U.S. troops at risk.

“The danger is that this material could be used by the enemy to incite violence against U.S. and Afghan service members,” he said.

The criticism was a departure for the Pentagon, which did not object publicly after news organizations posted the Marine urination video.

The Times said it was given the photographs by a soldier from the 82nd Airborne who wanted to expose “a breakdown in leadership and discipline that he believed compromised the safety of the troops.”

U.S. commanders said they were investigating whether poor unit leadership by non-commissioned officers could have played a role in the recent cases of misconduct, amid concerns that troops have become desensitized or worn out after multiple deployments.

Sen. Jack Reed. D-R.I., a former Army paratrooper and member of the Senate Armed Services Committee, said one possible factor is a lack of direct supervision. Under the military’s counterinsurgency strategy, many small units are dispersed across rural parts of Afghanistan, often without their platoon leaders or company commanders.

“They aren’t always there, so they physically can’t exercise the leadership,” he said.

Reed said the instances of misconduct are obscuring the military’s good deeds and effort to win the hearts and minds of the Afghan people. “This is one of the difficulties of this kind of operation, with counterinsurgency,” he said. “It is as much a political battle as a tactical one.”