US President George W Bush has said there will be no retreat from Iraq or from the war against terror.
Search operations and raids have been continuing
Mr Bush was speaking to US military veterans as the number of American deaths since the end of major combat operations on 1 May surpassed the number killed during the war.
Mr Bush told the gathering in St Louis, Missouri, that it was a choice between "civilisation and chaos".
Opposition politicians in the US have criticised his speech with one Democrat dismissing it as "empty rhetoric".
A US soldier was killed and two others wounded on Tuesday in an attack on a convoy in the town of Hamariya - about 25 kilometres (16 miles) north-west of Baghdad.
Figures released by the Pentagon showed that the number of deaths since 1 May had risen to 139, of whom 62 were killed by hostile fire.
Up until 1 May, 138 US troops had died in Iraq.
The BBC's Justin Webb in Washington says President Bush's speech has failed to quell the growing debate in the US about his administration's Iraq policy.
Sensing public concern about Iraq, the Democrats seized upon the speech and attacked it with unusual vigour, our correspondent notes.
Democratic presidential hopeful Bob Graham called the speech "the same old fluff, the same old empty rhetoric, the same old sugar coating of a very bad situation".
Dick Gephardt, another potential candidate who supported the war, said it was incomprehensible that more was not being done to get other nations to share the burden of bringing about peace.
Such criticism is a sign that the situation in Iraq is to become an issue if the president seeks re-election in just over a year's time, says our correspondent.
Mr Bush cited the examples of post-war Germany and Japan, arguing that while their reconstruction had taken years, not months, the effort had been worth it.
Mr Bush said that out of the 55 Iraq's "most wanted", some 42 had been captured or killed.
He added that almost two-thirds of al-Qaeda militants had been captured or killed but their network remained a threat to the US.
US marines have handed over control of the central city of Karbala to Bulgarian forces - hours after Polish forces in the city came under fire.
Polish troops confirmed their base had come under mortar attack but no-one was injured and no equipment damaged.
A multinational force led by Poland is to oversee one of Iraq's three post-war "stabilisation" zones -
an area 80,000 sq km (31,000 sq mile) in size in southern central Iraq, located between the US and UK areas.
Bulgarian troops are joining the force in Karbala which lies about 80 km (50 miles) south of the capital Baghdad.
The British charity Oxfam has announced it has withdrawn all international staff from Iraq because of the poor security situation.