The US President, Mr George W. Bush said last night Iraq's transformation will be a "massive and long-term undertaking," indicating an early US exit is considered unlikely.
He also said the broader US war on global terrorism would be lengthy, with new leaders of the al-Qaeda militant network likely to replace those captured or killed.
"From the beginning we have known the effort would be long and difficult, and that our resolve would be tested," Mr Bush said.
The White House billed the president's remarks as an update on the war on terrorism and on Iraq - where daily attacks on occupying US troops have threatened morale and cast doubt on the ability of the United States to transform Iraq into a friendly, stable country.
"The rise of Iraq, as an example of moderation and democracy and prosperity, is a massive and long-term undertaking," Mr Bush said. "We will stay on the offensive against the enemy, and all who attack our troops will be met with direct and decisive force."
US officials had hoped for a swift transformation in Iraq following the removal of President Saddam Hussein from power. The United States has about 150,000 troops in Iraq and the Pentagon is considering whether it might need to increase that force.
Attacks on occupying forces have killed 22 US and six British soldiers since May 1st.
Mr Bush's comments came as a USA Today/CNN/Gallup poll found that the share of Americans who said things were going well for US forces in Iraq dropped to 56 per cent from 70 per cent a month ago.
The figure is down from 86 per cent during the week of May 7th, when Mr Bush said major fighting in Iraq had ended and claimed that as a victory in his ongoing global war on terrorism.
The poll found 37 per cent believed the Bush administration deliberately misled the public about whether Iraq has serious weapons of mass destruction, up from 31 per cent a month ago.
Confidence that the United States would eventually capture or kill Saddam waned to 18 per cent, down from 36 per cent in March.