An Iraqi vice president defiantly threatened continued terrorist attacks on coalition forces Saturday after a homicide bomber driving a taxi cab lured four American soldiers to their deaths at a checkpoint outside the city of Najaf.

Hours after the attack, Iraqi state television said Saddam Hussein had awarded the killer two posthumous medals, and Vice President Taha Yassin Ramadan vowed such attacks will now be "routine military policy."

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He said thousands of Arabs are streaming into Iraq to help fight against the coalition.

"We will use any means to kill our enemy in our land and we will follow the enemy into its land," Ramadan said ominously at a news conference in Baghdad. "This is just the beginning. You'll hear more pleasant news later."

Later in the day, as darkness fell on the region, allied forces resumed their heavy bombing of the capital.

Reuters reported four heavy explosions in the center of the capital at 7:30 p.m. (11:30 a.m. EST), two more loud blasts at 10 p.m. and a series of explosions shortly before midnight. There also were reports of heavy artillery fire just north of the southern port city of Umm Qasr.

Also on Saturday, a spokesman for British Prime Minister Tony Blair said the commander of Baghdad's air defense forces had been replaced after Iraqi surface-to-air missiles, aimed at Western warplanes, missed and fell back on the Iraqi capital.

U.S. and British officials have suggested during the week that stray Iraqi anti-aircraft missiles -- not coalition attacks -- may have been responsible for two intense bombings that killed dozens of Baghdad civilians at two marketplaces.

Briefing reporters on condition of anonymity, the spokesman said new, unspecified intelligence indicated that U.S. and British bombing may not have been to blame for the explosions.

The bodies of four Americans were found in graves near Nasiriyah, the scene of heavy fighting in the past week, and there were reports out of the Pentagon that they were dismembered.

And Kurdish militiamen moved closer to the key prize of the north -- Kirkuk and its oil fields -- after Iraqi forces staged a sudden withdrawal to possibly plug defenses targeted by U.S. airstrikes.

In Najaf, the homicide bomber -- a noncommissioned army officer and the father of several children -- stopped his cab close to a military checkpoint on Highway 9, waved for help, and then detonated his explosives as the four American soldiers approached.

Capt. Andrew Wallace said the victims were with the 1st Brigade, 3rd Infantry Division.

Iraqi state television called the bombing the "blessed beginning on the road of sacrifice and martyrdom." It said 11 soldiers had been killed in the attack, and two tanks and two armored personnel carriers had been destroyed.

It was the first homicide bombing against U.S. and British forces since the invasion of Iraq began.

The attack came as coalition forces battled to quell paramilitary harassment in order to prepare for an all-out push toward Baghdad.

U.S. commanders said the attack would not force the coalition to make operational changes.

"We continue to place force protection as our highest priority, but that doesn't mean we're going to back into little holes and hide," said Col. Will Grimsley, commander of the 1st Brigade.

Maj. Gen. Victor Renuart, Jr, the U.S. Central Command's director of operations, said the attack was "a symbol of an organization that's starting to get a little bit desperate."

In Baghdad, Iraq's Information Ministry building was damaged in a pre-dawn U.S. missile attack. The building remained intact, but satellite dishes were destroyed, and Information Ministry officials said the 10th floor -- which housed an Internet server -- was gutted.

Elsewhere in the city, black-clad mourners gathered at a marketplace where Iraqi officials said dozens of civilians were killed by a coalition bomb. But despite still-smoking fires and intermittent explosions, Saturday saw the heaviest traffic on the streets of Baghdad since the war broke out. Many shops were open in the commercial districts and thousands of residents were on the streets.

In Kuwait, meanwhile, authorities said Iraq fired a missile of its own that damaged a popular shopping mall in Kuwait City.

Ground combat continued in southern and central Iraq, while U.S. forces pressed ahead with air and missile strikes aimed at weakening Republican Guard positions defending Baghdad. The latest strikes included attacks by Apache helicopter gunships of the 101st Airborne Division.

Some U.S. combat units were slowing their advance while supply and communications support is beefed up, but coalition officials said there was no broad order to delay the push toward Baghdad.

""It is purely a case of shaping the battlefield, getting our troops equipped and in the right place for the next part of the campaign," said Group Capt. Al Lockwood, a spokesman for coalition forces.

Thus far, according to coalition officials, the frequent attacks on supply lines by Iraqi paramilitary fighters have not derailed preparations for the expected all-out assault on Republican Guard divisions near Baghdad. But Lockwood acknowledged that the aggressive paramilitary activity had not been anticipated by U.S. and British war planners.

"What we've encountered is, yes, something slightly different: paramilitary forces that weren't in the war-game profile," Lockwood said. "We have contingency plans... they have been brought into action to deal with these forces and have not at all deflected us from achieving our objectives and maintaining our timeline."

In Kuwait City, a missile exploded early Saturday on a pier near a multilevel seafront shopping center, blasting out windows and causing two minor injuries. It was first missile to hit Kuwait City since U.S. troops based there invaded neighboring Iraq on March 20.

Iraqi authorities had no immediate comment on the Kuwaiti allegation, but said the explosion Friday evening at the Al-Nasr market in Baghdad was evidence that U.S. and British forces were targeting civilian areas.

Iraqi Information Minister Mohammed Saeed al-Sahhaf said Saturday that President Bush should be charged with war crimes in connection with the civilian deaths.

The U.S. Central Command said it was trying to determine what caused the market explosion, but repeated its denials that Iraqi civilian neighborhoods are targeted.

Overall, Iraq claims more than 4,000 civilians have been killed or wounded since the war began 10 days ago. In Baghdad alone, 68 people were killed and 107 injured late Friday and early Saturday in the market explosion and other blasts, al-Sahhaf said.

U.S. officials said the Information Ministry was targeted before dawn by Tomahawk cruise missiles, but the building remained intact. Al-Sahhaf used the foyer of a two-story building next door to the ministry building for his briefing.

South of Baghdad, Marines battled Iraqi fighters in and around the Euphrates River city of Nasiriyah, which lies at a junction of highways leading to Baghdad. Four Marines with the 1st Expeditionary Force, which is engaged in the battle, were reported missing.

The U.S. Central Command said American warplanes firing laser-guided missiles destroyed a building where some 200 Iraqi paramilitary fighters and members of the ruling Baath party were believed to be meeting Friday in the besieged southern city of Basra.

U.S. officials said they did not know the fate of the building's occupants after the attack, which targeted units loyal to Saddam that British officials say have clamped down on restive civilians in Basra.

British forces surround the city -- Iraq's second-largest, with a population of 1.3 million -- and want to open the way for badly needed humanitarian aid. They have yet to launch a full-scale assault, but darted in with tanks Saturday to destroy two statues of Saddam.

British officials said one of their soldiers was missing and believed killed, and five others injured, after armored vehicles came under attack in a possible "friendly fire" incident near Basra. The Defense Ministry said it was investigating reports that the soldiers from the Household Cavalry Regiment were fired on by U.S. warplanes.

At Central Command, Renuart said the United States has restricted the launch of Tomahawk cruise missiles over Saudi Arabia after complaints about errant strikes. He said some of the missiles had fallen onto Saudi territory, and U.S. experts would conduct a technical review before conferring with Saudi officials on whether the launches would resume.

Fox News' Bret Baier and The Associated Press contributed to this report.