|An estimated one million people witnessed the swearing-in ceremony in Washington DC [AFP]
Barack Obama has declared the US is "ready to lead once more" and promised "mutual respect" for the Muslim world after being sworn in as the 44th president of the United States.
The first African-American to assume the office said in his inauguration address on Tuesday "all other peoples and governments who are watching" that "America is a friend of each nation ... who seeks a future of peace and dignity".
Al Jazeera's Rob Reynolds, reporting from the US capital, said Obama's pledge was something of a rebuke to the outgoing president, George Bush, clearly implying that the US had failed to show leadership in the last few years.
The new president also warned the estimated one million people gathered in front of the US Capitol in Washington DC that the country faced many difficult challenges.
But he spoke of hope and resolve and urged Americans to usher in a "new era of responsibility".
"Today, I say to you that the challenges we face are real. They are serious and they are many.
"They will not be met easily or in a short span of time. But know this, America: they will be met. We must pick ourselves up, dust ourselves off and begin again the work of remaking America," he said.
Minutes after taking the oath of presidential office with his hand on a Bible used by Abraham Lincoln, Obama said: "To the Muslim world, we seek a new way forward, based on mutual interest and mutual respect.
"To those leaders around the globe who seek to sow conflict, or blame their society's ills on the West - know that your people will judge you on what you can build, not what you destroy."
Marwan Bishara, Al Jazeera's senior political analyst, said Obama's speech was aimed at convincing Americans that he will take a different course from Bush.
|Obama took his oath using a Bible that Abraham Lincoln used [AFP]
But Robert Fisk, a Beirut-based journalist for the London-based Independent newspaper, said the speech did not highlight any major shift in US strategy.
"I do not think there was a great difference from the rhetoric of Bush, but we didn't get taken through 9/11 again," he said.
Fisk said the speech was being "meagre on the Middle East" as it did not refer to the Palestinian issue.
"Many people in this region [the Middle East] are going to say 'didn't he see the pictures on TV in the last few days?'.
"It's the Middle East that will come back again and again and I don't think he chose to address it," he said.
Hours after his inauguration, Obama addressed members of the US Congress at a lunch which was overshadowed by the collapse of Edward Kennedy, the Massachusetts senator battling a life-threatening brain tumour.
Robert Byrd, 91, a West Virginia Democratic senator, was also taken ill. Both were reported to be in stable condition.
Obama, the new commander-in-chief of the US military, later reviewed a grand parade of marching bands and other performers.
The Obama motorcade then drove along Washington's Pennsylvania Avenue before the president and his wife, Michelle, got out of their car to make the last stretch of the journey to the White House on foot.
|The president and his wife walked the last part of their journey to the White House [AFP]
The couple was cheered by massive crowds that lined the street several rows deep.
Grace Clark, a spectator who had travelled from California, said she had been inspired by Obama's speech.
"It was a new beginning for me, which I was able to share with my daughter here. It gave me the sense that we all have responsibilities of trying to make changes in the future," she told Al Jazeera.
Torrey Pocock, a Republican voter, said he was in Washington to witness a "festival of democracy".
"For the country, given its past history [of racism], to put its trust in an African-American president is an incredible thing," he said.
"This is an opportunity to see a bloodless revolution, an opportunity to completely change regimes."