THE American infantryman controlling the checkpoint on the road to al-Nasiriyah was clad in so much body armour he looked like Darth Vader.

Dark goggles covered most of his face, a khaki scarf was wrapped around his nose and mouth. His M16 assault rifle was pointed at the windscreen of the saloon car, which was clearly being driven by a young woman who had young children in the backseat.

This did not stop the young soldier from screaming at the occupants to “step out of the vehicle and move to the side of the road”. How much of that muffled command the frightened woman understood was unclear, but as she hesitated and tried to comfort the youngest of her children, who was trying to clamber over the seat towards her, the infantrymen yelled even louder.

It was difficult to tell who was the more nervous. Rifles remained trained on the mother and children, who were made to stand 60ft away from their car while it was searched. There was no attempt to explain to the woman why this was necessary, but American patrols appear to treat everyone now as if they are suicide bombers.

You would not expect British commanders to criticise their allies publicly, but troops who have witnessed Americans at close quarters in this war are baffled at their approach to Iraqi civilians. British troops manning checkpoints in Safwan, Umm Qasr, al-Zubayr and Rumaillah were ordered yesterday to replace helmets with berets. A British military spokesman said: “It looks less aggressive, makes us appear more open and friendly.”

One captain in the Royal Marines, watching a US unit monitor a checkpoint, said: “The Americans are still behaving like invaders, not liberators. They behave as if they hate these people.”

Indeed, many American troops speak as though they do. You often hear them describe “Eye-rakis” in disparaging language. One US officer in charge of delivering humanitarian aid earlier this week likened the crush of people waiting to get hold of food and water to a pack of stray dogs. His troops’ idea of crowd control was to lash at those pushing to the front of the queue with fists and rifle butts, even firing shots into the air.

When Irish Guards were nearly mobbed by a crowd trying to grab the food that they were delivering to al- Zubayr this week, Major David Hannah urged his men to keep calm and to get the people to sit down.

“They need to have their dignity respected, and while this is a sticking plaster approach we need to make better contacts with locals to ensure the food goes to the needy,” he said.

British units have asked local worthies, such as hospital directors, teachers and anybody untainted by association with the regime, to distribute food aid as they see fit.

British commanders are appalled at how the Americans pulverise anything from afar before daring to set foot out of their armoured vehicles.

This was no better illustrated than in the first skirmish of the land war, where the American 15th Marine Expeditionary Unit was handed what should have been the easy capture of the seaport of Umm Qasr. Royal Marine officers watched incredulously as their US compatriots bombed and shelled the town for five days.

There is no doubt that the experience of nearly 30 years policing Ulster has taught British forces that the only way to root out gunmen is to patrol on foot, searching house by house. They did this in Bosnia, in Sierra Leone and Afghanistan.

The rhetoric of US soldiers is often provocative. When an American colonel was asked by The Times what the role of the Fifth Corps would be, he replied: “We are going in there, we are going to root out the bad guys and kill them.”

His men, grouped around him, grunted, whooped and punched the air as if they were watching a football match.

A British officer who saw this exchange shook his head and walked away, saying: “We are working from a different script but you won’t get anyone in Whitehall to admit it.”

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