This is war, and death is inherent, but what made Wednesday's scene so striking was the apparent joy that accompanied the brutality: the burning trucks, the cheering crowds, the charred bodies of Americans being mutilated, then hung from a trestle over the Euphrates River.
Americans die violently almost every day in Iraq, but the deaths are usually attributed to rockets or mortars from faceless combatants, or roadside bombs detonated from afar. Wednesday's attack on four civilian contractors in Fallujah was caught on film and gave face to the difficulty of the situation in parts of Iraq.
Attackers shot the contractors in their two vehicles, then set the SUVs ablaze, the military reported. Photographers at the scene captured cheering crowds pulling the charred corpses from the cars, beating them with sticks, then parading them through the streets. At least two bodies were hung from the bridge.
"Depending on the media play, this could be President Bush's Somalia moment," said Matthew Felling, media director for the Center for Media and Public Affairs in Washington.
"It will decide whether President Bush is combating militant Iraqis, or newly reluctant Americans. ... This is the day the revolution started being televised."
The pictures from Fallujah ran throughout the day on cable news channels and on newspaper Web sites. They immediately invited comparison to the images of jubilant Somalis dragging the broken body of a U.S. Army Ranger through the streets of Mogadishu in 1993, during an operation to oust a recalcitrant warlord.
Those photos led to the pullout of U.S. troops from Somalia. Experts in foreign policy say they don't expect Wednesday's pictures to affect U.S. policy in Iraq, but some acknowledged the televised attack could undermine Bush's assertion that the United States and its allies are making significant progress toward building a free and safe Iraq.
Plus, the attack followed a tough week: Bush's former anti-terrorism chief, Richard Clarke, told a commission investigating the Sept. 11, 2001, attacks that the Bush administration was fixated on invading Iraq and didn't do enough to combat al-Qaida. And March was the second deadliest month for U.S. troops in Iraq since Bush declared major combat operations over last May.
Marvin Kalb, senior fellow in the Washington office of the Joan Shorenstein Center on the Press, Politics and Public Policy at Harvard University, said Wednesday's pictures may "deepen the feeling of anxiety about going to war in Iraq" that many Americans feel, but he doubted they would change many minds.
Those who opposed the war will use the killings as proof the mission is impossible, he said. "For those Americans who feel that it was the right thing to do, it does raise questions, but I don't think it's going to dissuade them from believing ... it."
Nearly 600 U.S. soldiers have been killed in Iraq since the war began last March, and four more deaths, no matter how gruesome, aren't going to cause a major shift in public opinion, he said.
And in Somalia, President Clinton and the Congress panicked, not the public, said Alex Jones, director of the Shorenstein Center, who has studied opinion polls from the Somalia era.
"I think people are more sophisticated than they're given credit for," he said. Even in Vietnam, "the public opinion only turned when people began to believe that it was a war that could not be won."
But powerful images can move people and policy. Thirty years ago, a photo of a naked Vietnamese girl burned in an American napalm attack became emblematic of the mess in Vietnam. In January, a flash of Janet Jackson's breast led to tighter controls on broadcasters.
Howard Dean's primal scream - a wacky aberration in what had been an extraordinary candidacy - was replayed 633 times on three cable news channels and the major TV networks in the four days after the Iowa caucuses, said Felling, of the Center for Media and Public Affairs. And it essentially doomed Dean to the political margins.
"TV trends toward visceral and compelling footage, and what happened in Fallujah is nothing if not that," Felling said
"As much progress as the administration has made in Iraq, and as much as they talk about winning hearts and minds, these images go a long way toward refuting that premise. Even if these Islamists are in the minority, the images are powerful if they're being replayed ad nauseum."
Anita Sharma, an Iraq expert and director of the Conflict Prevention Project at the Woodrow Wilson International Center for Scholars, said America must remain committed to rebuilding Iraq, but she acknowledged the violence underscores how far the U.S.-led coalition must go before it wins the hearts and minds of the Iraqi people. An ungrateful Iraqi populace makes the case harder for people at home.
"What's troubling is when you see these types of grisly deaths, and then you see Iraqis rejoicing in them. That is the sickening part, and that's what plays in the mind of Americans," said Sharma.
Sharma spent five months in Iraq last year, working on reconstruction projects for the United Nations. She noted that Fallujah and other parts of west-central Iraq have received very little aid because they've been so hostile.
"I would characterize Iraq as a less stable place than it was a couple months ago for sure," Sharma said. "The instability in Iraq colors everything, and getting the security right is something that has to happen before you can begin moving forward in elections and reconstruction."
In the past week, attacks against U.S. forces have averaged 28 each day, the military said Wednesday. Within hours of the killings in Fallujah, and just 15 miles away, five U.S. soldiers were killed when their personnel carrier struck a roadside bomb. No pictures were available.