The people of Baghdad awoke Friday morning from the heaviest night of bombing since the war began to hear their country's defense minister warn that their city's streets would be a "grave" for invading US soldiers.
But as American troops inched their way toward the capital, their commanders were doing everything possible to avoid the nightmare prospect of house-to-house fighting in the capital.
US and British airplanes have flown nearly 1,500 sorties over the past 24 hours, according to an allied forces spokesman, many of them pounding elite Republican Guard positions ringing Baghdad.
Though US military leaders have acknowledged surprise at the strength of resistance that Iraqi troops, especially the irregular fedayeen, have mounted, they appear to be sticking to their original "inside out" strategy, hoping that a swift advance on Baghdad and an impressive display of armored might will cause President Saddam Hussein's regime to collapse.
"I don't think they are surprised at being surprised," says Paul Cornish, head of the Centre for Defence Studies at King's College in London. "They are getting to the later stages of the first phase of the campaign, and waiting to see if it will work."
US planners are also preparing for a longer war. Officials in Washington announced on Thursday night that Gen. Tommy Franks, in overall command of the allied campaign, would be doubling the number of US troops in the field, tapping forces now en route by sea around the Arabian peninsula and troops flown in from the United States.
More than 100,000 troops are expected to arrive in Kuwait in the coming days and weeks, to reinforce the 90,000 US soldiers already in Iraq.
"This is a good indication that General Franks needs more men," says Paul Beaver, an independent British military analyst.
"He doesn't have the combat power" to protect lengthening supply lines and engage irregular Iraqi forces left behind by the main US advance, Mr. Beaver adds. "The Americans have to decide now whether to push on or to consolidate."
In northern Iraq, Kurdish guerrillas opened the beginnings of a long-awaited second front on Friday, swarming over positions that Iraqi troops had abandoned along the line that had separated territory under President Hussein's control from the autonomous Kurdish area.
Overnight, US cargo planes had flown in helicopters and other equipment to strengthen the 1,000 man force dropped by parachute early on Thursday morning, in a move that seemed to herald a push on the northern oilfields around the city of Kirkuk.
Iraqi Defense Minister Sultan Hashim Ahmed predicted on Friday that US and British troops would have encircled Baghdad within the next five to 10 days, but warned that then "the enemy must come inside Baghdad, and that will be its grave.
"We feel this war must be prolonged so that the enemy pays a high price," he added, in comments to reporters.
Any close-quarters fighting in the capital would inevitably be bloody for troops and civilians, and US planners are clearly anxious to avoid the need for such an operation. US Defense Secretary Donald Rumsfeld hinted during a Senate hearing on Thursday at the possibility of a siege of Baghdad that might spark an uprising against Hussein.
He pointed out that Baghdad has a large population of Shiite Muslims "and they are not terribly favorable to the regime" dominated by Sunni Muslim officials. "They have been repressed," he added.
"Much depends on the Republican Guard" units currently enduring heavy US and British bombardment outside the capital, predicts Dr. Cornish. The better equipped and even more loyal Special Republican Guard has deployed inside Baghdad to keep the Republican Guard out in case of a coup attempt, he says, so neither force has trained to carry out the complex maneuvers that would be needed to compress both of them into the city under outside attack.
"The first (US) plan still has a lot of legs," Cornish says. "The cutoff point will come when allied troops are exhausted and simply cannot go any further, and we are about half way there."