After giving Congress the required notification for war, the Bush administration told Americans this evening to prepare for a war with Iraq that would cost lives, but that it hoped would be short.
"On the brink of war with Iraq, Americans should be prepared for what we hope will be as precise and short a conflict as possible, but there are many unknowns. It could be a matter of some duration, we do not know," White House spokesman Mr Ari Fleischer said.
"Americans have to be prepared for loss of life. Americans have to be prepared for the importance of disarming Saddam Hussein to protect the peace."
As Mr Fleischer was speaking more than huge convoys have moved across the Kuwaiti desert as 150,000 US-led combat troops have taken up battle positions for an imminent invasion of Iraq in the demilitarised zone along the Kuwait-Iraq border.
The zone extends five km (three miles) into Kuwait and 10 km into Iraq. It was not clear how far in the troops were. United Nations observers pulled out of the area on Monday.
President George W. Bush has given Saddam and his two sons until 1 a.m. tomorrow (Irish Time) to leave Iraq or face attack. "(At) 8 o'clock tonight the American people will know that Saddam Hussein has committed his final act of defiance," Mr Fleischer said.
The president is expected to make an Oval office speech in the event of war, but Mr Fleischer declined to say whether this would be before or after hostilities began.
His comments were some of the most direct by the White House on the possible costs of an Iraq war, which would be the first under a national security strategy announced last year that asserts a right to launch pre-emptive strikes on countries deemed a threat.
In what US officials describe as a "shock and awe" opening stanza of any war, over 3,000 satellite-guided bombs and cruise missiles will be launched from sea and air against Iraqi targets deemed vital to Saddam's regime.
"I think there will be such overwhelming firepower that to resist militarily will be futile," said one defence official. "It is going to be so swift and furious that they are not going to know what hit them."
The administration is expected to ask Congress for between $70 billion and $90 billion within days of the start of the war. The money would be intended to cover war costs, stepped-up domestic security and aid to Israel and Jordan.
Mr Bush notified Congress last night, under terms of a resolution passed in 2002 authorizing force against Iraq, that diplomacy had failed. The notice was required before or within 48 hours after the start of war. It was released today.
"Nothing that has occurred in the past 12 years, the past 12 months, the past 12 weeks or the past 12 days provides any basis for concluding that further diplomatic or other peaceful means will adequately protect the national security of the Untied States from the continuing threat posed by Iraq," or lead to the enforcement of UN disarmament demands, a report accompanying the notice said.
Saddam denies having such weapons. There have been no signs Saddam would leave, and Iraq vowed to defeat an invasion.
The president also spoke with British Prime Minister Tony Blair, his staunchest ally on Iraq, to congratulate him on overcoming a party revolt to win parliamentary backing to wage war on Iraq.
Agencies