He said: "If force is required...our armed forces have been given every tool and resource to achieve victory."
Mr Bush was giving a speech he makes every week on US radio.
The next few days are absolutely vital - Mr Bush is meeting British Prime Minister Tony Blair and Spanish Prime Minister, Jose Maria Aznar on Sunday.
Peace protests
And Britain's foreign secretary Jack Straw says war against Iraq is now 'much more probable.'
He told BBC Radio 4's Today programme that it would still be best to solve the crisis without military force but said "time is running out."
Meanwhile, anti-war demonstrations were taking place around the world again on Saturday.
Hear story
Iraq crisis timetable
Should we go to war with Iraq?
