Photos of naked prisoners heaped before smiling guards threaten to demolish the policies of a superpower -- the sole nation capable of global warfare brought to heel by snapshots from an Army reservist's pocket camera.

"One of the indelible icons of this war will be some of these images," said Tom Rankin, director of the Center for Documentary Studies at Duke University.

Whether they become icons in a war lost to national doubt that congealed around their emotional weight, or a war won despite their degrading influence, is yet to be seen. Members of Congress gathered behind locked doors yesterday to examine images so volatile the session was conducted under security reserved for military secrets.

The debate turned on whether more images -- photos of Iraqi prisoners in women's underwear, naked, tied up, being violated with light sticks -- should leave the secrecy of the Senate hearing room and be distributed in a world where they can now be seen simultaneously in both the White House and the bare walls of a Baghdad hut.

"These images can have a significant impact and potentially a lasting one and can make the difference between success or failure in Iraq," said James Dobbins, a former ambassador and now director of the RAND Center for International Security and Defense Policy. "We're clearly in the midst of an insurgency, and insurgencies aren't won by killing insurgents. Insurgencies are won by persuading the population to support you in marginalizing the extremists."

That phase of the anti-insurgency suffered a tremendous blow when photographs of torture and abuse at Abu Ghraib prison began circulating 10 days ago -- even though descriptions of the activities had been circulating for months in press accounts and the reports of human rights groups.

Vivid images have swayed policy in the past. Jacob Riis prowled the tenements of New York City in the early 20th century, and took searing photographs of the scandal of child labor. Dorothea Lange's photographs of Depression Era migrants generated emotional support for Franklin Roosevelt's New Deal.

Internationally, the Vietnam War photographs of Eddie Adams -- of a Saigon police chief executing a Viet Cong guerrilla with a pistol shot to the head -- and Nick Ut's image of 9-year-old Phan Thu fleeing naked from a napalm attack encapsulated and fed the American sense of pointlessness in Vietnam.

The Defense Department's Central Command announced in January that abuses at Abu Ghraib were under investigation. But it was the release of the photographs that set off a whirlwind of controversy.

"The way the photo makes us deal with these harsh realities is something that has been with us a while and helps explain why this is on the country's front-burner now," said Rankin. "If it wasn't for the photographs, we wouldn't be talking about it widely."

Nor would the discussion be so wide, nor so intense, absent the increased reach of global communications.

"It is very striking in the Middle East, with the spread of television stations that are prepared to seek out controversy and generate excitement, that viewers can now see real-time shots of military actions in ways that were utterly inconceivable as late as the 1991 war," said Patrick Clawson, deputy director at the Washington Institute for Mideast Policy. "That raises the temperature dramatically."

But Clawson and other experts doubt that the newest images of horror -- the beheading of American captive Nicholas Berg by terrorist kidnappers -- will translate into an effective counterpoint against the prisoner abuse photos. Part of the reason, said Clawson, is that policy leaders doubt the kidnappers' assertion that they acted in reprisal for the prison abuse.

"They would have seized on whatever the issue of the day was," Clawson said. Another American, journalist Daniel Pearl, was executed the same way in 2002, a year before the Iraq War began.

At their core, said Dobbins, the photos from Abu Ghraib are gripping precisely because of the double standard that exists between them and the grisly videotape of the Berg murder.

"We hold ourselves to a different standard. We've said we're different. We've tried to persuade them we're different," he said. "Of course there's a double standard. Wouldn't you want the United States held to a higher standard than Saddam Hussein?"