Was Karbala a sacred site for Iraq's majority Shiite population influenced military planning, 101st Airborne Aviaton Brigade commander Colonel Greg Gass was asked hours before Friday's strike?

"It's very important to us," he replied. "We are very well aware of Karbala's historical customs and the religious importance it holds for the Shiites.

"The last thing we want to do is cause any type of damage to Karbala and the Iraqi populace," he told AFP.

Brigade operations officer Major Bill Gayler went further, saying the pilots' instructions were to "mitigate any damage to protected sites".

"We'd be hard pressed to win the hearts and minds if we take out a religious facility and that's obviously not our intent," he said.

"We have gone to extreme measures as an army, not just a division, not to do any damage to those sites."

US authorities are hoping for a popular uprising as one way to overthrow Saddam, and the Shiites, who make up about 60 percent of the population but do not enjoy any political power, would be crucial in any revolt.

However the United States has not taken Shiite support for granted, with many members of the faith uncertain and even hostile to American soldiers trampling through their holiest sites.

Adding to the potential opposition is smouldering anger over the Shiite uprising after the 1991 Gulf War that failed without the expected US support.

Saddam wreaked vengeance on the Shiites in Karbala and elsewhere during and after his crushing of the rebellion, with tens of thousands reportedly killed and various sacred sites damaged.

Karbala, about 80 kilometres (50 miles) southwest of Baghdad, and Najaf, a further 80 kilometres south, hold massive importance for Shiites, with sacred shrines that attract thousands of pilgrims each year.

Karbala is where the Shiite martyr and the grandson of the prophet Mohammad, Imam Hussein, was killed and buried in 680 AD.

Hussein was killed fighting for the right to lead all Muslims and his death was the final act in the schism between Shiite and Sunni Muslims that exists to today. Shiite derives from the phrase Shiat Ali, or partisans of Ali.

Najaf, where fighting has raged throughout the week with US officials reporting 1,000 Iraqis killed, is the burial site of Imam Ali, the founder of what became the Shiite sect.

Ali was Hussein's father and Mohammad's son-in-law and cousin. His followers believed he should have been the prophet's successor.

Although Shiite Muslims make up a majority of Iraq's population, they have been consistently persecuted under the rule of Saddam, who is a Sunni.

Friday night's attack was a joint effort between the 101st Airborne Division and the airforce, according to Colonel Gass, and followed a series of bombings in the same area by navy warplanes earlier in the day.

The air assaults were seen as potentially the start of a major campaign to wrest control of Karbala, which is a vital gateway in the US military's push towards Baghdad.

The US army's 3rd Infantry Division, which has led much of the military assault north from the Kuwaiti border, is waiting on the outskirts of Karbala.

WAR.WIRE