U.S.-led forces closed in on the Iraqi capital Monday, meeting tenacious resistance from paramilitary fighters and Saddam Hussein's Republican Guard along the way. With attacks by irregular combatants in civilian clothes on the rise, wary troops were watching all Iraqis with increasing suspicion. 

In the closest battle yet to Saddam's seat of power, U.S. troops with the 3rd Infantry Division pushed early Monday into the Euphrates River town of Hindayah, about 50 miles south of Baghdad. Iraqi soldiers fired from behind brick walls and hedges with small arms and rocket-propelled grenades, and U.S. troops returned fire with 25mm cannon and machine guns. 

At least 15 Iraqis were killed and U.S. forces captured several dozen others who identified themselves as members of the Republican Guard - Saddam's best-trained and equipped fighters. Their uniforms carried the elite unit's triangular insignia and they said they were with the Nebuchadnezzar Brigade, based in Saddam's home area of Tikrit. 

In Baghdad, the headquarters of Iraq's information ministry was set ablaze after a predawn missile strike early Monday. Coalition attacks targeting leadership and command and control centers were carried out simultaneously by multiple B-1, B-2 and B-52 bombers, according to U.S. Central Command, which oversees the war in Iraq. 

With nightly aerial bombardments on the capital and ground forces advancing from the south, west and north, U.S. military leaders defended the pace of the war effort Sunday, answering criticism that they had underestimated the vigor of Iraqi resistance. 

"We have the power to be patient in this, and we're not going to do anything before we're ready," said Gen. Richard Myers, chairman of the Joint Chiefs of Staff. 

There is good reason for caution as troops face persistent danger from plainclothes killers and warnings from Iraqi officials that there will be more suicide attacks like the one that killed four Americans on Saturday. Iraqis said some 4,000 Arabs have come to Iraq to help attack the invaders. 

While it was not clear when the ground assault on Baghdad would begin, officials predicted Saddam's defenders would put up a brutal fight. 

"It's going to get more difficult as we move closer to Baghdad," Defense Secretary Donald H. Rumsfeld said. "I would suspect that the most dangerous and difficult days are still ahead of us." 

As part of the effort to clear the road for ground forces, Myers said airstrikes on Baghdad and its environs have reduced some Republican Guard units to less than half their prewar capacity. 

In northern Iraq on Monday, coalition aircraft pounded Iraqi positions in Kalak, a town about 20 miles east of the strategic city of Mosul. Iraqis could be seen running for cover along the treeless ridge west of the great Zab River. Kalak is at the border between Iraq proper and parts of the country held by minority Kurds 

In south-central Iraq on Sunday, the Army's 82nd Airborne Division killed about 100 "regime terror squad members" and captured about 50 Iraqi militants in the Shiite holy city of Najaf and another nearby town, Central Command said. It did not further identify the "terror squads." 

In the southern city of Nasiriyah, where fighting has been fierce for a week, Marines on Sunday secured buildings held by an Iraqi infantry division that contained large caches of weapons and chemical decontamination equipment. 

Also Sunday, a Marine UH-1 Huey helicopter crashed at a supply and refueling point in southern Iraq, said a spokesman, 1st Lt. John Niemann, in Kuwait. Three people aboard were killed and one was injured in the crash that occurred while the helicopter was taking off. 

British troops moved into villages surrounding the southern port city of Basra, where an outnumbered but tough core of Saddam loyalists have held off the coalition for about a week. As many as 1,000 Royal Marines and supporting troops, backed by heavy artillery and tanks, staged a commando assault in an eastern suburb. 

Coalition forces took about 30 Iraqi fighters prisoner and destroyed a bunker and several tanks, said British military spokesman Group Captain Al Lockwood. An unknown number of Iraqis were killed. One Royal Marine was killed in action Sunday, Lockwood told the British Broadcasting Corp. 

British forces in Basra have been working to flush out militants loyal to Saddam, he said, in some cases with the help of civilians. 

"The people of Basra are coming out, they're talking to us," Lockwood said. "We're gaining their confidence and they're beginning to provide us with valuable information about where these paramilitary forces are within the city and how they're operating." 

Ruling Baath party enforcers have shot civilians trying to flee Basra and forced regular troops trying to quit the fight to stay in it.