Some U.S. forces have paused on their push toward Baghdad, while coalition airstrikes pounded Iraq's information ministry and a meeting of paramilitary forces U.S. officials blame for atrocities.

The U.S.-led coalition controls 35 percent to 40 percent of Iraq's territory and 95 percent of its airspace, the Pentagon's top general said.

But near the central Iraqi city of Najaf a suicide bomber killed five Americans on Saturday at a highway checkpoint. An Army officer said the driver of the car signaled for help and then detonated explosives as the soldiers approached.

Meanwhile, American forces continued preparations for an expected ferocious battle against Iraq's best-trained and best-equipped troops: The Republican Guard forces arrayed outside Baghdad. Airstrikes, including the first heavy combat from a helicopter unit of the 101st Airborne, continued hammering at the elite Iraqi forces to soften them up for the eventual ground campaign.

Some Marine units took a break on their push toward the Iraqi capital Saturday in what commanders called an "operational pause." The troops worked to secure their lines of communications and wait for more of their comrades to catch up after heavier than expected attacks along the way.

Fierce combat continued in the Euphrates River crossing city of Nasiriyah, where Marines reported four troops missing Friday. U.S. military convoys and aircraft faced frequent attacks by both Iraqi troops and fighters in civilian clothes using rifles, rocket-propelled grenades and mortars.

Eight Marines remained missing from a Sunday battle near Nasiriyah in which Iraqi forces pretended to surrender but then opened fire on approaching troops, the military said. At least nine Marines were killed, officials said.

The Pentagon blames such attacks on Iraqi paramilitary forces like the Fedayeen Saddam, which Defense Secretary Donald H. Rumsfeld calls "death squads." The military claimed a strike Friday on a building in the southern city of Basra where about 200 such paramilitaries had gathered.

The strike from two U.S. F-15s used bombs with a delayed fuse, which explodes after it penetrates the building, to hit the target without damaging a Christian church 300 yards away, a statement from U.S. Central Command said.

The Army's 101st Airborne Division sent out AH-64 Apache helicopters to attack Republican Guard positions south of Baghdad. Officers at the scene said the helicopters destroyed tanks, armored personnel carriers, other vehicles, a fuel depot and a communications tower.

Two of the attack helicopters were damaged when they made hard landings at their temporary base in the Iraqi desert, but no one was seriously hurt.

Joint Chiefs of Staff Chairman Gen. Richard Myers insisted Friday at a Pentagon briefing that fighting along key U.S. supply lines was not militarily significant. He and Rumsfeld said the push to Baghdad would not be derailed.

Rumsfeld hinted the United States had operatives working inside Baghdad and other Iraqi cities.

"We have people inside talking to people, dealing with people, arranging things," Rumsfeld said in response to a question about the mood of Baghdad's 5 million residents.

To underscore the message that the war is going well, Myers showed a map of Iraq detailing about 40 percent of the country that he said was no longer under Saddam's control.

The areas included Kurdish zones in the north which have been autonomous since the early 1990s, a large swath of Iraq's western desert where special operations forces have been hunting for missiles, and a triple-peaked area of southern Iraq where the Army and Marines are pushing toward the capital.

The U.S.-led coalition also has air supremacy over about 95 percent of Iraq, Myers said. The exception: The capital and Saddam's hometown of Tikrit, where surface-to-air missile sites and other air defenses have not been completely knocked out.

Coalition forces have fired more than 650 Tomahawk cruise missiles and dropped more than 5,000 precision-guided bombs on Iraq since the war started, Myers said.

A Tomahawk strike hit Iraq's Information Ministry headquarters in downtown Baghdad early Saturday, Central Command said. Footage from video cameras stationed on the building showed a bright flash and a thunderous explosion that shook masonry off nearby buildings. At midmorning, however, the ministry building appeared intact.

In Kuwait, officials said Iraq fired a missile of its own into a Kuwait City shopping mall. The missile was the first to hit the city since the United States launched its invasion of neighboring Iraq on March 20.

British and U.S. planes flew more than 1,500 missions over Iraq Friday, including 700 strike sorties, a military official said. The vast majority of those were bombing and strafing in support of coalition ground forces, the official said.

Also, two U.S. Navy F/A-18s bombed an al-Samoud missile battery about 25 miles northwest of Basra on Friday, U.S. Central Command reported.

The coalition has used that air superiority to pound the Republican Guard, particularly elements of the Medina and Hammurabi divisions stationed to the north, west and south of Baghdad.

Myers said Republican Guard units defending the city were "dug in."

"They could be consolidating to make a defense. It doesn't make any difference. The outcome is certain," said the Joint Chiefs chairman. He showed overhead photos that he said showed Iraqi military units -- possibly of the Republican Guard -- were trying to hide tanks and other military equipment in a residential neighborhood south of Baghdad.

Up north, airstrikes have focused not only on Iraqi military targets but on the positions of Ansar al-Islam, a radical armed group the United States says is linked to the al-Qaida terrorist network. U.S. forces used an airfield secured by members of the Army's 173rd Airborne Brigade to bring in more supplies and troops for a northern front.