WASHINGTON -- Fighting street by street, U.S. Army troops punched their way into the outer defenses of Baghdad early today and battled Iraqi forces over a bridge across the Euphrates River at Hindiya, 50 miles south of the capital.
The Americans captured several dozen Iraqis who identified themselves as members of the Nebuchadnezzar Brigade of Saddam Hussein's Republican Guard.
At least 15 Iraqi troops were killed in the fighting in Hindiyah, between the sacred city of Karbala and the ruins of ancient Babylon.
The action came as U.S. military forces continued to tighten their grip on the outskirts of the Iraqi capital yesterday, pummeling troop divisions from the air in preparation for a major assault on Republican Guard units.
American-led forces waged one of the heaviest air bombardments of the war, concentrating fire on Iraqi troop formations while also striking government installations and knocking out Baghdad's telephone system. Another round of airstrikes began early this morning.
South of the capital, allied soldiers uncovered more evidence that Iraq has prepared its troops for a chemical or biological attack, To the north, special forces stormed a complex described as a "massive terrorist facility," seizing documents and a computer, and beginning a search for the poisons thought to have been made there.
Iraqi forces, meanwhile, were said to be reinforcing their defensive positions outside Baghdad in anticipation of an American attack. Iraqi military leaders claimed that more than 4,000 Arab sympathizers have entered the country to wage guerrilla-style strikes and suicide attacks against U.S. and British troops.
Even with soldiers and Marines encircling Baghdad, U.S. officials seemed less than eager to begin the long-envisioned ground campaign against Iraq's capital city, apparently preferring to slowly squeeze Saddam Hussein's forces and let the pressure build.
"We have the power to be patient in this, and we're not going to do anything before we're ready," Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, told CNN's Late Edition. "We'll continue to draw the noose tighter and tighter."
But Myers and others also made clear that the war's toughest fight might still be ahead and that the risks of terrorist attacks or a chemical or biological weapons strike increase each day that forces move closer to a Baghdad showdown.
"There are difficult days ahead," Defense Secretary Donald H. Rumsfeld said in an interview on Fox News Sunday. "And to the extent the Republican Guard poses difficulties, which we expect them to, there will be dangerous days ahead. Baghdad is not going to be easy."
President Bush returned yesterday from a weekend at Camp David but had no public comment on the war.
Three Americans were killed and one was injured yesterday when a Marine UH-1 Huey helicopter crashed at a supply and refueling point in southern Iraq, bringing to 40 the number of U.S. troops who have died in the war. The cause of the crash was uncertain, though Pentagon officials said the helicopter did not appear to have taken enemy fire.
In Kuwait, 15 U.S. soldiers were injured when a man in civilian clothes drove a pickup truck into a crowd of soldiers at a military base. Investigators did not know whether the incident was deliberate, but it came at a time of heightened alert for such attacks because of the suicide bombing a day earlier that killed four U.S. soldiers.
Iraqi officials raised the specter yesterday that more suicide attacks can be expected. They reportedly paid $34,000 to the family of the man who carried out Saturday's attack, in addition to two posthumous medals awarded earlier. And Deputy Prime Minister Tariq Aziz referred to suicide attackers as "heroes" and "freedom fighters" in an interview with ABC News and said "there will be others."
Closer to the fight, journalists and U.S. military officials reported cautious advances toward a possible confrontation outside Baghdad. U.S. officials said troops are closing on the capital and that some are within 49 miles of the city. Myers said that the airstrikes were concentrating on Iraq's better-trained Republican Guard units and that those forces are at less than half their prewar strength.
Troops from the Army's 101st Airborne Division circled the Shiite holy city of Najaf, 100 miles south of Baghdad, and were preparing for perilous house-to-house battles to root out Hussein loyalists. The Army said it killed about 100 paramilitary fighters and captured about 50 Iraqis. Whether the soldiers planned to seal off the city or storm into it was unclear. Commanders expressed concern about the heavy damage that a fight might inflict on the many holy sites and shrines within the city.