The US military is investigating two incidents in which American soldiers killed at least 26 Iraqi civilians and then claimed that they were either guerrillas or had died in cross fire.
The growing evidence of retaliatory killings of unarmed Iraqi families, often including children, by US soldiers seemingly bent on punishing Iraqis after an attack, will spark comparisons with the massacre of Vietnamese villagers at My Lai in 1968.
US troops have been notorious among Iraqis for their willingness to shoot any Iraqi they see in the aftermath of an insurgent attack. But it is only now that convincing and detailed information is becoming available about the killings.
In the most recent incident, in the town of Ishaqi north of Baghdad last week, Iraqi police said that US troops had shot 11 people, including five children, in their home. The local police chief, Colonel Farouq Hussein, said that all the dead had been shot in the head, according to autopsies. "It's a clear and perfect crime," he said. In an incident in the town of Haditha in western Iraq on 19 November last year, US soldiers went on a rampage in a village after a bomb attack and killed at least 15 civilians, according to witnesses and local officials cited by Time magazine in an investigation.
The US military first claimed a roadside bomb had killed a US Marine, Miguel Tarrazas, along with 15 Iraqi civilians caught in the blast. Later, a military statement said "gunmen attacked the convoy with small-arms fire" and in returning fire the Marines killed eight insurgents.
But after Time presented the US military with what Iraqis said had happened, an official investigation found that 15 of the civilians had been deliberately killed by US soldiers.
The bomb attack on the US Humvee took place at 7.15am. Eman Waleed, a nine-year-old child, lived in a house 150 yards from the explosion. "We heard a big noise that woke us all up," she recalled later. "Then we did what we always do when there's an explosion: my father goes in to his room with the Koran and prays the family will be spared harm."
The Marines claim they heard shots coming from the direction of Waleed's house. They burst in to the house and Eman heard shots from her father's room. They then entered the living room, where the rest of the family was gathered. She said: "I couldn't see their faces very well - only their guns sticking in to the doorway. I watched them shoot my grandfather, first in the chest and then in the head. Then they killed my granny."
The US soldiers started shooting in to the corner of the room where Eman and her eight-year-old brother, Abdul Rahman, were cowering. The other adults in the room tried to protect the two children with their bodies and were all shot dead. Eman and her brother were both wounded.
"We were lying there, bleeding and it hurt so much. Afterwards some Iraqi soldiers came. They carried us in their arms. I was crying, shouting, 'why did you do this to our family?' And one Iraqi soldier tells me, 'we didn't do it. The Americans did it'."
The Marines' explanation is that they heard the sound of a Kalashnikov being readied to shoot and had then fired their weapons. The Marines say they were fired at from a second house, where they broke down a door, threw in a grenade and opened fire. The eight who died in the second house included the owner, his wife, the owner's sister, a two-year-old son and three young daughters.
In a third house the Marines searched four young men were shot dead. A military investigation decided these were insurgent fighters, along with four others killed in the street.
The Marines later delivered 24 bodies to a hospital in Haditha, claiming they had been killed by shrapnel from a bomb. Dr Wahid, the director of the hospital, said: "It was obvious to us there were no organs slashed by shrapnel. The bullet wounds were very apparent. Most of the victims were shot in the head and chest - from close range."
An US military investigation decided the deaths were "collateral damage". Relatives were paid $2,500 (£1,400) for each of the dead.