The Pentagon has taken control of a television channel used by Iraqi state television and begun beaming programmes from a US C-130 Hercules aircraft, writes Conor O'Clery from New York.
The first item Iraqis saw when the service was launched yesterday was a message from Mr Bush - recorded while he was in Belfast on Monday - declaring: "Your nation will soon be free."
It was followed by a similar message with Arabic subtitles from the British Prime Minister, Mr Tony Blair, who assured Iraqis that coalition soldiers were "friends and liberators, not your conquerors".
The content of the channel, named Nahwa Al-Hurrieh - Towards Freedom - will be controlled by the US and British military, and is aimed at convincing Iraqis and the rest of the Arab world that US and British troops are not a hostile invasion force.
The display of US flags by troops in Baghdad has contributed to an image problem, with the conservative New York Post yesterday splashing the photograph of Saddam Hussein's statue with an American flag over his head with the headline "Liberty!"
The broadcasts will also be heard on Iraqi radio, and texts in Arabic distributed in leaflet form throughout Iraq.
In addition, the US and British forces started publishing a newspaper called The Times in southern Iraq with an initial circulation of 10,000, the White House said.
"Our only enemy is Saddam's brutal regime - and that regime is your enemy as well," Mr Bush said.
The goals of the coalition for Iraq's "good and gifted people" were clear and limited, he said.
They included the end of Saddam's reign and the elimination of weapons of mass destruction.
They would also provide security, respect religious traditions and create a representative government for a sovereign nation.
"You deserve to live as free people," he said.
"And I assure every citizen of Iraq: Your nation will soon be free."
Mr Blair said: "We did not want this war, but in refusing to give up his weapons of mass destruction, Saddam gave us no choice but to act."
The British Prime Minister promised that Iraqi oil, which made Saddam Hussein "one of the richest men in the world", would help Iraqis prosper.
"Iraq will not be run by Britain or by the United States, or by the United Nations. It will be run by you."
"Saddam Hussein and his regime plundered your nation's wealth. While many of you live in poverty, they lived lives of luxury.
"Saddam became one of the richest men in the world, his money stolen from you, the Iraqi people," he said.
Acknowledging that US-led forces had left many Iraqis to their fate after encouraging a rising in the wake of the 1991 Gulf War, Mr Blair said: "You thought Saddam's rule was being ended, but he stayed, and you suffered.
"That will not happen this time. This regime will be gone and ended."
In New York, several thousand demonstrators turned up at a rally at the World Trade Centre site to support the troops in Iraq. New York governor Mr George Pataki said to cheers that metal from the toppled statue of Saddam Hussein in Baghdad should be used in a girder of a new building at ground zero.
Meanwhile, Mr Bush's job approval rating has risen alongside the military successes in Iraq, with three in four Americans agreeing that he is doing a good job, his best performance since June 2002.
Eight out of 10 supported his decision to go to war, and two out of three said the war was going "very well", up 19 points in less than a week.
An overwhelming majority worry that winning the peace may prove to be more difficult than winning the war, according to the Washington Post-ABC News poll.