President Bush on Tuesday defended military operations in Iraq, saying U.S. troops would not abandon the country in the face of increasingly deadly attacks.

Just hours before Bush spoke at the White House, a suicide bomber struck in the western Iraqi city of Fallujah. A man driving a Toyota sedan stopped near a boys school and detonated his deadly cargo, killing himself and at least five people, including schoolchildren.

Tuesday's attack came as U.S. troops and Iraqi workers retrieved personal belongings from rubble at the headquarters of the International Committee of the Red Cross in Baghdad, which was struck along with three police stations in a wave of bombings Monday. Aid workers questioned whether it was still possible to work safely in the country.

At a Rose Garden news conference, Bush compared the people who bombed the Red Cross headquarters with those who attacked the United States on Sept. 11, 2001.

"Basically what they're trying to do is, is cause people to run. They want to kill and create chaos. That's the nature of a terrorist," Bush said.

"They're not going to intimidate America, and they're not going to intimidate the brave Iraqis who are actively participating in securing the freedom of their country," the president said.

With polls showing eroding support among Americans for his Iraq policies, Bush said the White House never underestimated the dangers in Iraq after he declared an end to major combat operations May 1.

A weekend Gallup/USA Today/CNN poll showed 50 percent of Americans disapprove of the way Bush is handling the Iraq conflict, up from 18 percent six months ago. The poll surveyed 1,006 adults Friday through Sunday and had a margin of error of plus or minus 3 percentage points.

"I said Iraq's a dangerous place in which we've got hard work to do. There's still more to be done," Bush said.

Later Tuesday, a U.S. soldier was killed and six others were wounded in a rocket-propelled grenade attack in Baghdad, the military reported.

Tuesday night, eight heavy explosions were reported in Fallujah and three explosions rocked Baghdad. No immediate details on casualties or damage from the blasts were available, but the thundering sounds in the nighttime skies above the capital were reminiscent of the U.S. bombing campaign earlier this year that helped drive Saddam Hussein's government from power.

The car bomb in Fallujah, 40 miles west of Baghdad, exploded in front of a power station about 30 yards from the school and 100 yards from its apparent target, a police station, witnesses said. U.S. soldiers sealed off the area after the blast, which set parked cars ablaze.

There was no claim of responsibility for the bombing. Fallujah is in the "Sunni Triangle," a region of predominantly Sunni Muslims and Saddam loyalists in central Iraq known for its ardent resistance to the U.S. occupation.

In Baghdad, the cratered street in front of the Red Cross headquarters was flooded with water from broken mains. Sidewalks usually busy with Iraqis rushing to work and school were silent.

Many Red Cross staffers were attending the funerals of two colleagues among 12 people killed outside the offices. "Today is a day of mourning for us," spokeswoman Nada Doumani told reporters.

Antonella Notari, chief spokeswoman for the International Committee of the Red Cross in Geneva, said no decision had been made on whether to evacuate non-Iraqi staffers.

Doumani said the organization was weighing its response to the mayhem but would not leave Iraq after 23 years of work through three wars.

Bush blamed the spate of violence on Saddam loyalists and terrorists who have entered Iraq from other countries.

He said U.S. forces have beefed up border patrols in Iraq and the United States has asked Iran and Syria -- which the United States accuses of supporting terrorism -- to cooperate.

Six months after Bush declared major combat operations over while speaking from an aircraft carrier deck in front of a huge banner proclaiming "Mission Accomplished," the president was asked Tuesday by a reporter whether he now felt that declaration had been premature.

Since then, 217 U.S. troops have died in Iraq -- 115 from hostile fire -- bringing to 355 the number of U.S. fatalities since Bush launched the war in March.

The president on Tuesday disavowed any connection with the "Mission Accomplished" message. "The 'Mission Accomplished' sign, of course, was put up by the members of the USS Abraham Lincoln, saying that their mission was accomplished," Bush said.

One of the Democratic candidates for president, Wesley Clark, pounced on Bush for his comments. "Politicizing the mission of those troops in the first place was bad theater and diminished the office of commander in chief," said Clark, a retired four-star Army general.

"To now turn his comments on those very troops is outrageous," Clark said. "Instead of trying to blame the sailors and soldiers, the president owes our troops in harm's way and the American people a plan to bring peace to Iraq and stability to the region."

Another Democrat running for president, Sen. John Kerry of Massachusetts, accused Bush of substituting rhetoric for results.

"Landing on an aircraft carrier and saying 'mission accomplished' didn't end a war," Kerry said, "and standing in the Rose Garden and stating that 'Iraq is a dangerous place' does nothing to make American troops safer."

Another Democratic contender, former Vermont Gov. Howard Dean, called on Bush to transfer oversight of the occupation of Iraq from the Pentagon to the State Department.

"This president appears to lack the leadership skills required to do what is necessary to successfully stabilize and reconstruct Iraq before the window of opportunity closes," Dean said. "U.S. troops and taxpayers are suffering as a result."

With members of the House and Senate wrestling over the best way to fund Bush's request for $87 billion for military operations and reconstruction in Iraq and Afghanistan, the president reiterated his opposition to a Senate plan to provide some of the money in loans.

Bush has insisted on U.S. reconstruction aid in the form of grants that don't have to be repaid.

"Let's don't burden Iraq with loans," said Bush, who is working with his foreign counterparts to restructure some of the more than $100 billion Iraq already owes to Russia, France, Germany and others.

Bush said private investment and Iraqi oil revenues would make up for the shortfall between money pledged for reconstruction -- $20 billion from U.S. taxpayers and $13 billion from the rest of the world -- and the $56 billion the World Bank and United Nations estimate Iraq will need over the next four years.

In other developments:

• Coalition forces in Iraq detained two Al-Jazeera staffers after allegations that they had prior knowledge of a car bombing Monday in Baghdad, the editor of the Arab satellite television station said. Coalition military officials said they understood some journalists had been detained but had no details.

• The editor of an independent Iraqi weekly newspaper was shot and killed Tuesday on the roof of his office building in the northern city of Mosul, police said. His daughter said he had been threatened because of his writings.

• Unknown gunmen assassinated a deputy mayor of Baghdad in an apparent hit-and-run shooting, the U.S. occupation authority reported Tuesday. Faris Abdul Razzaq al-Assam, deputy mayor for technical services, had returned from last week's international Iraq donors' conference in Madrid, Spain, when he was shot Sunday, the Coalition Provisional Authority said.

 The Associated Press contributed to this article. Bob Deans' e-mail address is bdeans@ajc.com. Craig Nelson's e-mail address is cnelson@ajc.com.