"You are killers, not murderers. You are warriors not war criminals. Don't cross that line."
Those were the words of a US officer to his men before they took part in the recent assault on the Iraqi city of Falluja.
Just days later, one US marine was in the spotlight, with questions being asked about whether he was a murderer and a war criminal.
His shooting of a wounded Iraqi, caught on tape and beamed around the world since, has raised questions about the degree of military restraint and has fanned Arab resentment.
After interim Iraqi Prime Minister Iyad Allawi - the Falluja campaign's staunchest supporter - voiced his concern over the incident, the International Committee of the Red Cross (ICRC) sharply criticised the "utter contempt" for humanity shown by both sides in the conflict.
The shooting occurred on 13 November during the search of a mosque. A trooper raised his rifle and shot point blank at an apparently unarmed, wounded Iraqi who was slumped against one of the walls.
The marines said the rifleman was withdrawn from combat pending the results of an investigation, but the graphic footage had already made tempers boil in the region, months after the scandal over US troops' abuse of inmates at the Abu Ghraib prison.
But reports from newsmen embedded with the US troops during the assault launched on 8 November suggest that the shooting may not have been an isolated incident.
Instead, it may have simply been the only one caught on camera, an illustration of the looser rules of engagement authorised for the Falluja offensive.
The shooting of a wounded Iraqi
has caused an outcry
"The enemy can dress as a woman, the enemy can be faking to be dead," said one company commander to his marines before entering the heart of the city. "So shoot everything that moves and everything that doesn't move," he said.
The photographer embedded with this unit, which carried out some of the most dangerous missions on the frontlines of the Falluja battle, said the rules of engagement were gradually modified as the situation evolved.
"A marine was killed when a unit entered a house. They pulled out and dynamited the building, but when they moved back in, an arm stuck out from under the rubble and threw a grenade," he said.
The photographer, who did not wish to identify his unit, said the fear of human bombers combined with the discovery that fighters were taking amphetamines and adrenaline prompted his platoon to take new measures.
"From that point on, the rule was the so-called 'double tap': two bullets in every body," he said.
Troops were told to fire 'two
bullets in every body'
The night before the assault began, the order came down that troops could shoot any male on the street between the ages of 15 and 50 if they were viewed as a security threat, regardless of whether they had a weapon.
When marines asked a gunnery sergeant for clarification, he told his men if they saw any military-aged males on the street "Drop 'em."
The marines had issued special rules of engagement, particularly for the Falluja operation, that emphasised anyone considered a danger could be shot.
After one marine was killed and five were wounded on the second day of the assault, the military command ordered platoons to spray homes with machine-gun and tank fire before entering them, in an effort to kill members of the resistance lurking inside waiting for them.
The US military said on 14 November that more than 1200 "rebels" had been killed since the start of the operation, the largest toll in Iraq since the 2003 invasion. It said on Saturday that 54 marines and nine Iraqi soldiers were killed in the clashes.
Children are among the victims
of the Falluja assault
However, no casualty toll for civilians has been made known. Hospital staff and other witnesses have reported the deaths of dozens of civilians, including children.
Although the vast majority of Falluja's residents fled the city before the onslaught, some families decided to stay behind to guard their homes and possessions, and many are feared to have been killed in the violence.
The Iraqi Red Crescent Society said on Thursday that about 150 families were still trapped inside Falluja, as the US-led operation was winding up, with troops still fighting the last pockets of resistance.
Dr Nazar al-Obaidi, a physician in Fa lluja told Aljazeera: "The situation is very bad in the city; there is no water or electricity, lack of food. Coalition and Iraqi forces are distributing bottled water to civilians but it is not enough"
"An epidemic may occur due to lack of clean water, a lot of areas are filled with stagnant water which rolled into homes, this and the lack of proper sewage system. People are suffering from diarrhoea," he added.
According to The New York Times, quoting the ICRC, about 800 civilians have been killed in Falluja since the US assault on the city began on 8 November.
The paper cited the story of one family using a car to flee the carnage into the city only to come face to face with a marine squad who had taken control of a mosque as a defence position.
"A barrage of bullets followed. Minutes later, Ms Abd Allah's mother lay bloodied and dying in the rear seat, glass shards strewn about her. Ms Abd Allah, hit in the back by a bullet, collapsed into her mother's lap. Three men in the car were lightly wounded," the paper reported.
When US marines realised they may have killed civilians, they rushed to check on the casualties. Their support Iraqi National Guard advised they kill the survivors, but the marines held off and provided medical assistance when it was determined the people in the car were not part of the city's resistance groups.