"We are on the way to accomplishing the mission and achieving victory," said White House spokesman Scott McClellan, on the three-year anniversary of a speech in which the president, standing on the deck of the aircraft carrier USS Lincoln, pronounced major US combat operations over in Iraq.
Mr Bush's overly-optimistic assessment that "major combat operations" were over in Iraq and the now-infamous "Mission Accomplished" banner have been the subject of much criticism ever since, with thousands of US forces and Iraqi civilians killed in escalating violence over the past three years.
The Pentagon said that as of last Friday, 2,401 US forces were killed in Iraq, including 1,886 since Bush's aircraft carrier speech.
Mr Bush put the event behind him on Monday, declaring that after months of sectarian strife, Iraq had turned a corner after selection of a unity government.
"(We) are going to work with the new leadership to strengthen our mutual efforts to achieve success, a victory in this war on terror," he said in brief remarks delivered on the White House lawn.
Opposition jibes
But opposition Democrats, who long have considered the "Mission
Accomplished" incident among the administration's most embarrassing gaffes, could not resist needling Mr Bush about the administration's missteps in Iraq.
"In honor of today's 'Mission Accomplished' anniversary, allow me to remind the president of some of his 'accomplishments' in Iraq," US Representative Rahm Emanuel, a Democratic leader in the US House, wrote in a press release.
Congressman Emanuel enumerated a long list of administration mistakes, including predictions "that the Iraq conflict would take no more than five months" and "that our troops would be greeted as liberators."
Other members of the opposition party piled on, with top Senate Democrat Harry Reid calling Monday "a sad anniversary of a sorry public relations stunt."
Democratic US Senator Ted Kennedy used the milestone to slam the administration, while honoring the US war dead and their survivors.
Families flee
Meanwhile about 200 Shi'ites rallied outside the Green Zone in Baghdad to demand that US and Iraqi forces do more to stop insurgent attacks and help Iraqis who have fled their homes because of sectarian violence.
Tens of thousands of Iraqis have left mixed Sunni-Shi'ite areas because of such killings, some carried out by militias allied with Iraqi political parties. A surge in such attacks began after the February 22 bombing of a Shi'ite shrine in Samarra in northern Iraq.
Sectarian violence has forced about 100,000 families across Iraq to flee their homes, one top Iraqi official said.
Adil Abdul-Mahdi, one of the country's two vice-presidents, estimated that 100,000 Iraqi families - 90 per cent of them his fellow Shi'ites - had fled their homes to escape attacks by rival religious sects.
Abdul-Mahdi's estimate was higher than any offered so far by Iraqi officials, who have placed the figure at about 15,000 families, or about 90,000 people.
At the same time Iranian forces shelled a border area used by Iranian Kurdish rebels for a second straight day, forcing some families to flee their homes but causing no casualties, a Kurdish official said.
"It was so heavy that it forced families in these villages to flee the area to find shelter with their relatives," said Mustafa Qader, a member of the political bureau of the Patriotic Union of Kurdistan party.
In Baghdad, Iraq's central government could not immediately confirm the latest attack.