KEY POINTS:
In the still of Baghdad's hot midnight, among thick palm groves that line the Diala River to the city's south, the sound of helicopters strafing the tree line a few hundred metres distant seems sickeningly close.
The noise is an ugly bass drilling sound that jars even the US soldiers in their vehicles.
It is not quite random firing into the farmland and groves. It is a calling card to the mortar teams who use these secluded spots to fire into the distant Green Zone. An hour or so earlier, it was artillery firing out of one of the forward operating bases, the explosions echoing among the tall, spare trees. The soldiers call it "area denial". This weekend the firing has an extra urgency. Following tips from Iraqi civilians, the hunt is on for a new and deadlier kind of rocket, modelled on one of those used by Hizbollah, the al-Sharooq. In the pictures the soldiers have been given it looks like an artillery shell with jet boosters, fired out of its own launcher. It can fly six miles with an accuracy far greater than any of the rockets or mortars deployed so far. It can penetrate armour and the hardened shelters of the Green Zone - a new and dangerous escalation in the war in Iraq. Tonight, sources say, it will be fired for the first time.
"It is like searching for a needle in a haystack," says Lieutenant Johnathan Lee of the 2/17 Field Artillery, leading a patrol of Humvee vehicles. But that is not all. His presence on the ground, talking to the farmers and drivers he encounters, is also designed to discourage the mortar teams. It is the human face of "area denial".
Lee, 24, is not certain whether the tips are bad intelligence meant as sabotage or simply a rumour that has become inflated in the telling. If mortars are fired, he explains politely to any Iraqis he encounters, the gun crews will detect the source and fire back. Then there is the risk that civilians will be hurt. The alternative, he says, is to tell his forces when the mortar teams are in the area. Then life will improve.
But many Iraqis still regard the Americans as the aggressors and shield the mortar teams. Others are simply afraid of retaliation from militant groups. It is a Catch-22. The soldiers try to stop the rockets before they are fired, but in reality the best way to catch the rocket teams is after their cargoes of metal and explosives are already arcing through the air.
It is dangerous for the American soldiers to linger too long after dark on their anti-mortar and rocket patrols. The night before it had been a different neighbourhood, Zafraniya, where we had been searching for the mortar teams, not in the woods but in an area of rough, dusty football pitches enclosed by poor housing.
A little later several mortars land at the nearby US base at Rustamiya from one of Zafraniya's neighbourhoods - or muhallas. "We patrol the scrubland. Then they fire from inside muhallas," says an exasperated Captain Dave Smith, who is responsible for liaising with the local neighbourhood council.
"We have two enduring operations here," Smith says. "They are called Happy Town and Sad Town. Any time we cause any damage with counter fire to mortar launches we go in and assess the damage, test the atmospherics and ask people why they allowed mortars to fire from by their houses. We try to placate the locals. That is Happy Town.
"In Operation Sad Town, we lock down the neighbourhood. We search houses and wake people up. We have the psy-op [psychological operations] truck go round broadcasting. But there are always people who will just say: 'Oh? We didn't hear the explosion when the mortar was launched'
- OBSERVER
