US President George W Bush has promised that America will not pull out of Iraq as a result of the continuing attacks on its forces.
Bush: We will stay on the offensive
The president was speaking as concern grows in the US about the level of American casualties - and on a day when six of its soldiers were injured in two separate attacks in Baghdad.
The US military said that three soldiers were wounded when explosives were thrown at their convoy on the outskirts of the city.
Another three were injured when a military vehicle was destroyed by a bomb near one of the city's main universities.
Hardly a day has gone by since the so-called end of hostilities on 1 May without an attack on coalition forces.
BBC Washington correspondent Justin Webb said senior politicians of both main parties have been pressing the White House to be clearer about the nature of the commitment the US is going to have to make if Iraq is to be put on the road towards democracy.
At a military swearing-in ceremony, Mr Bush talked of the massive and long-term undertaking that would be necessary.
Previously he has stressed that the 230,000 US troops would not stay in Iraq a moment longer than they needed to.
He told the audience: "We appreciate their service under difficult circumstances and their willingness to fight for American security and Iraqi freedom.
"As Commander-in-Chief I assure them we will stay on the offensive against the enemy. And all who attack our troops will be met with direct and decisive force."
He said some groups believed they had found an opportunity to force America to leave Iraq before freedom was established.
But they would not succeed, he said, as Iraq had been liberated as promised and America would help create representative government as promised.
The latest attacks on US troops came as hundreds of Iraqis chanted anti-American slogans in the flashpoint town of Fallujah at the funerals for nine people killed in an overnight blast at a mosque, which locals blame on US forces.
Among those killed in the Fallujah explosion was the mosque's imam Sheikh Laith Khalil, who resided there and gave theology lessons to students.
US troops are being targeted by resistance fighters
Residents in Fallujah say that the large explosion was caused by an American missile, a charge the US military denies.
"There was no US warplane involved. There was no artillery from US troops. It was simply an explosion inside a building adjacent to the mosque," Colonel Joseph Disalvo, commander of US forces in the town, 50 kilometres (30 miles) west of Baghdad said.
Vows of revenge
Our correspondent says that whatever the truth the incident has fuelled anger at the Americans and some in Fallujah say they now want revenge.
Mourners at the funerals for those killed chanted "America is the enemy of God!" and "Avenge the killings".
The town has been a hotbed of tension since April when 20 people were killed by American troops during a demonstration.
Mohammad Owdeh, a local resident, told Reuters news agency: "These explosions are a message to the Americans because they have done nothing for the Iraqi people. There will be more and more explosions."
At least 16 American soldiers have been killed since the war was declared over in May, but the chief US administrator in Iraq, Paul Bremer, has dismissed recent attacks as the predictable and increasingly desperate response of the ousted regime.
Although they appeared co-ordinated locally, there was no evidence the attacks were part of a centrally-controlled campaign, he said.
Suggestions that troops are facing an organised insurgency were earlier dismissed by US Defence Secretary Donald Rumsfeld, who insisted they were not becoming bogged down in a Vietnam-style guerrilla war.