Coalition missile attacks rocked Baghdad Friday morning, as U.S.-led ground troops advancing on the Iraqi capital continued to meet stiff resistance from Iraqi forces.

Coalition forces at as-Sayliyah camp in Qatar Friday said two missiles struck a communications tower in Baghdad disrupting Iraq's national communications network.

A Central Command spokesman in Qatar, Brigadier General Vincent Brooks, told reporters earlier that his forces will strike civilian installations, if they are also being used for military purposes. "There are a number of facilities throughout Iraq that on their surface would seem like normal things. Maybe it's a telephone switch, but it doesn't only take care of the commercial population, the civilian population," he said. "It is also used as a command-and-control network and a key node inside of that."

More than a dozen explosions rocked Baghdad during the night, as coalition missiles struck military command and communications installations.

Meanwhile, coalition ground troops clashed with Iraqi troops and paramilitary forces near the central Iraqi cities of Najaf and Nasiriyah and around the southern city of Basra.

Iraq's information minister, Mohammed Saeed al-Sahaf, warned coalition troops will face heavy resistance, if they invade Baghdad and said he thinks the war could go on for months.

VOA's Deborah Block, traveling with U.S. marines in central Iraq, said resistance there has been greater than originally expected. "The resistance by the Iraqi army has been more fierce than what the Marines encountered while crossing the Kuwaiti border a week ago," she said. "This may be partly due to the fact that U.S. troops appear to be coming in contact more often with the Iraqi Republican Guard."

Coalition leaders warned that troops could expect fierce resistance when they move on Baghdad. Defense Secretary Donald Rumsfeld told a Senate hearing that Iraqi's elite Republican Guard would likely present the greatest challenge. "It will require the coalition forces moving through some Republican Guard units and destroying them, or capturing them, before you will see the crumbling of the regime," he said.

U.S. officials announced that 100,000 additional U.S. troops were being sent to Iraq to bolster the 300,000 forces already in the region. And troops that landed in northern Iraq Thursday were preparing landing sites for the arrival of more forces from the Italy-based 173rd Brigade.