It was the sort of situation experts were warning about months before the military campaign in Iraq began, a nightmare scenario for U.S.-led troops on the ground.
On Sunday, U.S. Marines pushing their way northward across the Euphrates River were approached by an Iraqi vehicle waving a white flag near the southern Iraqi city of Nasiriya.
Assuming the vehicle was packed with Iraqi civilians wishing to surrender to coalition forces, the Marines awaited the approach of the surrendering Iraqis.
But it turned out to be an old trick from the bag of devious military deceptions, one with deadly consequences.
U.S. military officials said the Iraqi vehicle was packed with members of the Fedayeen Saddam, or "Saddam's Men of Sacrifice," a notoriously violent paramilitary group specializing in counterinsurgency operations for the regime in Baghdad.
Within minutes, according to reporters on the scene, there was mayhem in the area. The Iraqi fighters, dressed in civilian clothing, opened fire on the Marines, using small arms, assault rifles and some rocket-propelled grenades.
About 50 Marines were wounded in the ensuing melee, while a mortar attack apparently destroyed one of the Marines' vehicles before the wounded were evacuated.
Counterinsurgents Harassing U.S. Rear Guard, Says Military
Hours after reports of the ambushes came to light, the Fedayeen Saddam, a force believed to be largely made up of brutal, unemployed youth, shot into the international limelight.
U.S. military sources told ABCNEWS they believed Iraqi commanders dispatched Fedayeen fighters from Baghdad to Nasiriya over the past two weeks.
The deceptions were planned in advance, said military sources, and the fighters were meant to bolster regular army soldiers, whose loyalty to Saddam Hussein is considered questionable, the sources added.
During a press briefing at Central Command Headquarters in Qatar today, allied commander Gen. Tommy Franks said U.S. forces had "intentionally bypassed enemy formations," but he accused the Fedayeen of harassing U.S. rear guard in columns moving northward in southern Iraq.
"We know that the Fedayeen has in fact put himself in a position to mill about, to create difficulties in rural areas," said Franks. "I can assure you that contact with those forces is not unexpected," he added.
And they are not only attacking coalition military forces. A senior administration official said multiple intelligence reports show the Fedayeen — wearing U.S.-type army fatigues — have come into villages and executed locals who refuse to join them in guerrilla fighting.
Thugs and Louts
But some experts have raised doubts about whether Fedayeen could have conducted Sunday's ambushes on U.S. troops.
"First of all, the Fedayeen is used for domestic operations; they have no military training," said Ibrahim al-Marashi of the California-based Center for Nonproliferation Studies. Al-Marashi has done an extensive study on Saddam's labyrinthine military and civilian security organizations.
"I really don't think the Fedayeen could have carried out those operations. It is mostly made up of thugs, and is by no means is it a professional fighting force. It has been erroneously referred to as an elite fighting force, when in reality it is known for its brute force, rather than fighting prowess."
According to ABCNEWS analyst Toby Dodge of the University of Warwick in England, the Fedayeen is more likely to be used in urban warfare situations, especially when coalition troops are expected to enter big cities such as Basra and Baghdad.
"It would be unlikely to see them so early in the campaign," said Dodge. "They would be one of the final groups thrown into the fight, when the Marines reach Baghdad."
‘Odai’s Private Militia’
One of the most unpopular Iraqi paramilitary groups to have sprung up after the 1991 Gulf War, the Fedayeen Saddam, is a notoriously violent security unit founded in the mid-1990s by Odai Hussein, Saddam's eldest and, by all accounts, most troubled son.
Comprised primarily of young men from Saddam's own al-Bu Nasser tribe and other Sunni-dominated tribes from the region around his hometown of Tikrit, the Fedayeen is believed to number between 18,000 and 40,000.
"The Fedayeen Saddam is basically Odai's private militia, that is very selectively recruited — it does not have a mass mobilization like the al-Jaysh al-Sha'bi [Iraqi People's Army]," said al-Marashi.
"But they basically receive no formal training and are used to crush domestic dissent," he said.
Women Beheaded in Public
With their black outfits, including, at times, a black balaclava, the Fedayeen caught the attention of the international community in 2000, when human rights groups recorded several witness accounts of public executions of women in the streets of Baghdad and the southern port city of Basra.
According to witness reports, several women were publicly beheaded outside their homes in 2000 and 2001 by Fedayeen death squads in what was called a "cleanup" of "prostitutes."
Even given Iraq's human rights record, the executions came as a shock for Iraqi human rights activists. "It was a very new phenomenon, the first time women in Iraq have been beheaded in public," said Muhannad Eshaiker of the California-based Iraqi Forum for Democracy in an interview with ABCNEWS.com earlier this year.
"Many of the women were professionals, some of them wore hijab [Islamic veil] and had been outspoken against the regime or their families were opposed to the regime," he said. "It was terrible. It's the worst way to shame a woman in Iraqi society."
Top of the Paramilitary Pecking Order
In the grisly pecking order of violent vigilante justice meted out by various Iraqi security units, experts say the Fedayeen ranks at the very top. "I don't think the ordinary Iraqi policeman, even the undercover policeman, would do such a thing," said Eshaiker.
"For the most, there are some honest people trying to make a living, some of them genuinely believe they are serving their country. But the Fedayeen, there's no way to control the Fedayeen — it's the most brutal force comprised mostly of young men who can't get into universities and who wouldn't otherwise make it in life."
In a country where more than a decade of economic sanctions have shrunk the middle class and impoverished all but the political elite, many Iraqi men, not surprisingly, look to the vast security services for steady employment and a means to gain access to power.
"They are paid better than regular Iraqi soldiers," said al-Marashi, "and so they are loyal to Saddam."
For his part, Dodge echoes al-Marashi's assessment. "The Fedayeen are just people who were recruited because they had nothing better to do — thugs, unemployed, youngsters — [they are] hardly trained at all, and would be expected not to put up a very tenacious fight at the end."
ABCNEWS' Martha Raddatz in Washington contributed to this report.