On another day of U.S.-led airstrikes on Baghdad and coalition forces attacking Iraqi troops and installations, Iraqi state television said an army officer carried out a suicide bombing attack, which killed four American soldiers.
Iraq's Vice President Taha Yassin Ramadan praised the "martyrdom" operation.
He told reporters that suicide bombings will now become "routine military policy" and that Iraqis will use "any means" necessary against the enemy. Ramadan identified the bomber as Ali Jaafar Hammad al-Naamani.
"We call them martyrdom operations because the one who commits suicide is desperate and not a person who has faith in his country, freedom and honor and reaches the level of offering blood to save his people," he said.
Iraqi television said President Saddam Hussein had awarded two posthumous medals to al-Naamani.
It was the first suicide bombing against U.S. and British forces since they invaded Iraq. The attack came about a week after the Palestinian militant group urged Iraqis to use suicide bombings against coalition forces.
On Saturday, a senior Hamas member praised the suicide car bombing. Isma'eel Haneya told United Press International in Gaza that carrying out such attacks by the Iraqi people "is showing how awful the massacres and the crimes that are committed by the American and British forces against the Iraqis."
In Saturday's attack, a U.S. military officer said a taxi signaled for help, but when the soldiers approached the car, it exploded. The suicide car bombing happened at a military checkpoint near the city of Najaf, about 80 miles south of Baghdad.
"The attack was "a symbol of an organization that's starting to get a little bit desperate," Maj. Gen. Victor Renuart said in a briefing at U.S. Central Command in Doha, Qatar. The soldiers were from the First Brigade of the U.S. Third Infantry Division.
In Washington, Maj. Gen. Stanley McChrystal told reporters Saturday's suicide bombing won't change the military's "overall rules of engagement, but clearly will require great care" with regard to force-protection efforts.
At a news briefing Saturday, Pentagon Spokeswoman Victoria Clarke condemned Iraq's tactics, including suicide bombings, posing as civilians, waving white flags and the shooting at coalition forces.
"These flagrant violations committed by the (Iraqi) military will not make our forces give up and go home ... they're quite wrong about that," Clarke told reporters. "Every day Saddam (Hussein) is losing control of more of the country."
Meanwhile, U.S.-led coalition airstrikes continued across Iraq and through the night into early Sunday targeting Iraqi military and "irregular" targets.
Military commanders reported two battlefield successes -- an airstrike that destroyed a building near Basra that apparently killed 200 Baath Party officials and an Apache helicopter attack that killed at least 50 Iraqi soldiers near Najaf.
"Each time we make one of these attacks, we continue to degrade the regime, we continue to degrade their capability," said Renuart. "And in a very systematic approach, we are moving nicely down the road."
In the southern city of Nasiriyah Saturday, U.S. Marines using Cobra helicopter gunships, tanks, armored vehicles, mortars and artillery carried out attacks against Iraqi resistance. A number of Iraqi tanks had been destroyed, the report said. The operation is the latest effort to secure Nasiriyah, a city of about 500,000 people on the Euphrates River.
U.S. Central Command confirmed that they were investigating whether four bodies found in shallow graves near Nasiriyah, the site of fierce fighting for the past week, were that of U.S. military personnel.
Eight soldiers of the Army's 507th Ordnance Maintenance Company have been listed as missing since running into an ambush there last Sunday.
Renuart at his briefing said that a team of military morticians was conducting an investigation.
"I can't tell you whether they were soldiers who were in that engagement and were killed in the engagement and subsequently buried. I can't tell you for sure they're 507th (Company) soldiers."
McChrystal added: "In fact our Marines did find a shallow grave with some remains in them. We're not sure who they are at this point."
He declined to confirm a report that one of the bodies had been mutilated.
In Doha, Renuart announced that the United States had stopped firing Tomahawk cruise missiles over parts of Saudi Arabia after some missiles landed in Saudi territory.
"We have agreed with them to conduct a review of those launch procedures and make sure we don't have a systems problem that we might not be aware of," he said. "Once that is completed, we will go back to the Saudis and work to resume those (launches) when it is appropriate."
Renuart said the Tomahawk missile restrictions will not present an operational problem, and that routes will be used over other parts of the kingdom that will not endanger civilian populations.
In his weekly radio address Saturday, President George W. Bush said the Iraqi regime controls only a small portion of the country.
"The fighting is fierce and we do not know its duration, yet we know the outcome of this battle: The Iraqi regime will be disarmed and removed from power. Iraq will be free," Bush said in the address.
The Pentagon in the past few days announced that another 120,000 troops are being sent from the United States, adding to the roughly 140,000 U.S. ground troops in Iraq and Kuwait and another 100,000 sailors and airmen supporting the operation on aircraft carriers and on air bases. Another 45,000 British troops have been deployed as well. Officials said the new deployments had been planned all along.
Still, outside strategists said the United States faced a looming decision: Whether to essentially lay siege to Baghdad and wait for the new troops to arrive over the next several weeks, or proceed to attack the Republicans Guards entrenched around the city and go into Baghdad, where Iraqi leaders have vowed to fight to the death.
The methodical pace of the coalition effort was running up against intense anger from the Arab world, and pictures from the bombing of the Baghdad market Friday -- regardless of what happened -- were sure to inflame matters.
(With reporting by Pamela Hess from the Pentagon, Richard Tomkins with the 5th Marine Regimental Combat Team, Gassan al-Khadi in Baghdad, Kathy Gambrell at the White House, Seva Ulman in Ankara, Turkey, Martin Walker in Kuwait City, Hussein Hindawi in London, Eli J. Lake at the State Department and William M. Reilly at the United Nations.)