It started with an unsolicited e-mail. The writer said he’d read some of the articles Los Angeles Times reporter David Zucchino had written from Afghanistan. He was impressed. He also mentioned that he had some information that he believed was imperiling “the discipline, security and good order” of American troops in the country.

Zucchino had never met or even heard of the writer. But like any curious reporter, he was intrigued. Over the next two months, he kept up a correspondence and met the man on three occasions.

The information the man offered was a bombshell: 18 grisly photographs of American troops mugging and posing triumphantly with the remains of Afghan insurgents who had blown themselves up in attempted or actual suicide bombings.

The Times’ decision to publish two of the photos Wednesday had world-shaking consequences. The Pentagon and White House condemned the troops’ behavior while also protesting the photos’ publication because of concerns about retaliation. Afghan President Hamid Karzai on Thursday called the soldiers’ actions “inhumane and provocative” and suggested that the photos were another reason foreign troops should accelerate their departure from the country.

Readers weighed in by the thousands. Some were outraged by the photos, some by their publication. Others supported and cheered the soldiers’ behavior.

Once again, the media’s role in portraying the brutality of war was in question.

For his part, Zucchino, a Pulitzer Prize-winning foreign correspondent, says his newspaper made the right call after weeks of internal deliberation and pre-publication consultations with Pentagon officials.

“It’s our responsibility to report fully on the mission in Afghanistan, and it was important to publish these photos to tell the full story of the war,” he said in an interview Thursday. “We’ve reported aggressively, including [articles] about the sacrifice and heroism of the troops. This is one more aspect.”

Zucchino, 60, says he believes that his source’s motivation was exactly as he described in his original e-mail — that the soldiers’ actions violated the U.S. military’s general code of conduct. The source, whom Zucchino has promised not to identify, was a member of the 82nd Airborne, the division in which the soldiers in the photos served.

Despite the soldier’s distaste for what the photos showed, “he also understood the state of mind of these guys,” Zucchino said. “Their buddies had been killed by [improvised explosive devices] and maimed. It’s something they live with every day.”

At the same time, his source understood that the specific nature of the Afghanistan war might lead to these kinds of photos. “I’ve been embedded with Marines, and they complain all the time about how the enemy won’t engage in a direct fight,” Zucchino said. “So when [soldiers] come across their enemy or body parts, you can see the temptation to celebrate a little bit. They’re amped up, and they’re frustrated.”

The release of the photos, which were shot in 2010, was another in a series of recent episodes that created massively negative reaction toward the U.S. presence in Afghanistan. In January, a video surfaced of Marines urinating on the bodies of dead Taliban fighters; in February, Afghans violently protested the burning of copies of the Koran on a U.S. base. Last month, a U.S. soldier was accused of killing 17 Afghan civilians in a shooting spree. Some American military sources have suggested that these events may have sparked apparent reprisals by Afghan troops against their foreign allies.

Even so, Zucchino dismisses the Pentagon’s objections that running the photos might put Americans in Afghanistan at greater risk. “From my experience, the insurgents don’t need any extra motivation to attack us,” he said. “It’s a very dangerous place over there. They face a lot of risks already.”

Another journalist with decades of experience in disclosing U.S. military misfeasance endorsed the Times’ decision to publish.

“Reporters are reporters, and editors are editors,” said Seymour Hersh, who exposed the My Lai massacre during the Vietnam War and the abuses at the Abu Ghraib prison in Iraq in 2006. “They made the call they had to make. . . . These things happen in war. It’s dehumanizing.”

The photos, Hersh said, “remind us that war is terrible. That’s our job. It’s not our job to be on the team. If we had done our job of holding the Bush administration to the highest standards possible, we might have been more skeptical” about the rationale for the invasion of Iraq.

Questioning those in power, Hersh said, “does not make us unpatriotic or disloyal. Our mission is to tell it the way it is.”

“The two photos published were chosen because they clearly and unambiguously depict conduct that the Army described as inappropriate,” Times editor Davan Maharaj wrote in an online chat with the paper’s readers. “In examining the full set of images, we set aside others on grounds of taste, relevance or repetitiousness. Some were too gruesome. Others were very similar to the two images already chosen or were difficult to interpret.”

The newspaper declined to publish 16 other photos that included soldiers posing with dismembered body parts. It also did not make the photos available for wire-service distribution. The Washington Post has not published them.