The US President, George W Bush, has said the consequences of failure in Iraq would be unthinkable.
In a nationally televised news conference, Mr Bush said he would stake his re-election on a successful outcome in Iraq. He said that despite a few tough weeks, any comparison with Vietnam would be wrong.
The president also said the 30 June timetable for handing sovereignty back to the Iraqis would be met. He did not reveal who would take over the governing of Iraq at that stage.
Mr Bush said the violence in Iraq over the past few weeks had been serious, but he said it was not a civil war or a popular uprising. He said most of the country was stable.
Addressing the families of US troops, he said America would finish the job of the fallen and that, if needed, more troops would be provided.
Asked about the increasing number of Americans who disapprove of his handling of the situation in Iraq, Mr Bush said he did not make decisions based on poll numbers.
He said freeing Iraq was an historic opportunity to change the world, and added that the decision to succeed in Iraq had already been made and would not change.
Ashcroft before 9/11 commission
The US Attorney General, John Ashcroft, has robustly defended the Bush administration against charges that it ignored the terrorist threat from al-Qaeda ahead of the 11 September attacks in 2001.
Appearing before the commission inquiring into the attacks, Mr Ashcroft claimed that decisions taken during Bill Clinton's eight-year administration had blunted the effectiveness of America's counter terrorism agencies.
