Allied soldiers inched toward Baghdad on Sunday and pressed their campaign on a southern redoubt of Saddam Hussein loyalists, trying at every turn to gain trust from Iraqi citizens and stay safe from those who may be combatants in disguise.

The military campaign has increasingly become a confidence-building one, too, and not only in Iraq. U.S. war leaders, deployed on the Sunday airwaves, defended their strategy as a sound one and cast the painstaking pace of recent days as a virtue.

“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.

U.S. and British allies reported increased contacts with ordinary Iraqis on many fronts Sunday, a development measured — like the march toward Baghdad — in wary steps.

The reason for the caution was clear: persistent danger from plainclothes killers and warnings from Iraqi officials that there will be more suicide attacks like the one that took the lives of four Americans in Najaf. Iraqis said some 4,000 Arabs have come to Iraq to help attack the invaders.

Airstrikes on Baghdad continued Sunday night and into today against Iraqi leadership targets, command and control centers and communications facilities, Pentagon officials said. A fire was burning at the government’s Information Ministry after the overnight strikes.

The Army’s 101st Airborne Division surrounded Najaf on Sunday and was in position to begin rooting out the paramilitary forces inside the city, said Command Sgt. Maj. Marvin Hill.

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

A Marine UH-1 Huey helicopter crashed Sunday night at a forward 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.

Questions grew in Washington over the war’s pace.

Democratic Sen. Jay Rockefeller of West Virginia said the U.S.-led invasion was clearly facing more Iraqi resistance than anticipated and the war plan probably would have to be adjusted to deal with that.

“I consider them not to be trivial setbacks,” he said on CNN’s “Late Edition,” but rather “in the category of major problems.”

Gen. Tommy Franks, the coalition commander, said, “One never knows how long a war will take.”

Close to 100,000 U.S. service members are in Iraq, supported by about 200,000 in the theater and with 100,000 more on the way.

U.S. officials said coalition ground forces were closing in on Baghdad from the south, west and north — the southern front lines now 49 miles from the capital. Myers said airstrikes had reduced some units of the Republican Guard, Saddam’s best-trained forces, to less than half their prewar capacity.

British troops moved into villages on the fringes of Basra, the southern city where an outnumbered but tough core of Saddam loyalists have held off the coalition for about a week.

Up to 1,000 Royal Marines and supporting troops, backed by heavy artillery and tanks, staged a commando assault in a Basra suburb, killing some 30 Iraqi fighters and destroying a bunker and several tanks. Officials said Operation James — named for James Bond — was the Marines’ largest mission so far.

Defense Secretary Donald H. Rumsfeld said in Washington that the British were getting “increasing assistance from the local people as to where the death squads are located, where the thugs are. And they’re systematically working them over.”

The British first said they had captured an Iraqi general, but British military spokesman Will MacKinlay later told BBC television that the report was wrong, attributing the mistake to “the fog of war.” The spokesman said British troops had killed a number of Iraqi officers.

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

“As we win the trust of the Iraqi people,” said British Maj. Gen. Albert Whitley, “they’re pointing these people out, and either we’re targeting them or we’re detaining them.”

Rumsfeld offered a frank assessment of why many Iraqis have been slow to embrace allied soldiers even in some areas of the country unfriendly to Saddam.

He noted that the Shiite population in and around Basra rose up against Saddam after the 1991 Gulf War. “The United States and the coalition forces left, and they were slaughtered” by the tens of thousands, Rumsfeld said.

For that reason, “I’m inclined not to urge people to rise up until we’re close and we can be helpful.”

Whitley, commander of coalition efforts to secure areas for humanitarian shipments, said: “We did not really appreciate what 12-plus years of fear can do to people. They’re looking to see who hits them next.”

That concern was voiced in the British-controlled southern seaport city of Umm Qasr.

“The British army is here, we are safe,” said Yasser Hassan Ghanim, 22, who has been unemployed since running away from the Iraqi army in 2001. “But we are afraid the armies will go back, just like in 1991.”

After the suicide attack at Najaf and continuing trouble from combatants out of uniform, every apparently innocuous Iraqi man in the path of the allies is getting a hard second look. Nervous U.S. troops warned approaching drivers Sunday they would be shot if they did not leave the area.

Still, with handshakes, candy for the children and chitchat in broken Arabic or through an interpreter, U.S. soldiers were making acquaintances.

In a 10-mile advance toward Baghdad on Sunday, bringing them within 50 miles of the capital, soldiers of the 3rd Infantry Division encountered a dozen farmers waving white flags attached to sacks of flour.

Capt. Chris Carter, the commanding officer, pulled back his convoy of hundreds of armored vehicles to avoid damage to the farmers’ run-down shanties. One of his officers brought fistfuls of candy for the milling children.

There were warm smiles and handshakes even as nearby U.S. artillery fired volleys at the city of Al-Hindiyah on the Euphrates River.

The U.S. Central Command said the latest targets hit by coalition aircraft included military facilities at the Abu Garayb Presidential Palace, the Karada military intelligence complex and the barracks of a major paramilitary training center, all in different sectors of Baghdad.

Several telephone exchanges in the city also were hit Sunday, as well as a train loaded with Republican Guard tanks.

In Kuwait, a man in civilian clothes ran a white pickup truck into a group of U.S. soldiers standing by a store at their base, Camp Udairi, injuring 15 people, one of whom was hospitalized.