Washington - Barack Obama was sworn in as the 44th President of the United States on Tuesday, becoming the first African-American president in the country's 233-year history.
Standing on the West Front of the US Capitol and putting his left hand on a Bible used to swear in his role model President Abraham Lincoln, in 1861, the 47-year-old Mr Obama took the 35-word oath of office around Tuesday noon, administered by Chief Justice John Roberts.
The huge crowd that congregated on the vast green of the National Mall and nearby streets burst into thundering cheers and applause when the new president completed his swearing-in with the traditional finish line "So help me God."
Faced with daunting challenges including a worsening economic recession and two wars in distant countries, the new president, who had just made history, pledged that his administration would take "bold and swift" action to bring the country out of crisis.
"Starting today, we must pick ourselves up, dust ourselves off and begin the work of remaking America," he said in an 18-minute inaugural address.
"What is required of us now is a new era of responsibility," he told fellow Americans, adding that "those of us who manage the public's dollars will be held to account" so as to "restore the vital trust between a people and their government."
To a world increasingly weary of the American unilateralism, Mr Obama promised to seek "even greater cooperation and understanding between nations," and to seek "a new way forward, based on mutual interest and mutual respect" when developing relations with the Muslim world.
He also pledged to help the poor nations and urged the rich ones to discard their "indifference."
Heading the first new administration since the 11 September terror attacks in 2001, Mr Obama took a tough stand against America's enemies.
"For those who seek to advance their aims by inducing terror and slaughtering innocents, we say to you now that our spirit is stronger and cannot be broken; you cannot outlast us, and we will defeat you," he said.
Well known for his oratory skills, Mr Obama in his speech refrained from overplaying the significance of his inauguration as the country's first black president.
He only stressed the "noble idea" that "all are equal, all are free and all deserve a chance to pursue their full measure of happiness," and praised the country's liberty and creed that made it possible for "a man whose father less than sixty years ago might not have been served at a local restaurant" to "stand before you to take a most sacred oath."
After an inaugural luncheon at Congress, Mr Obama and his wife, First Lady Michelle, took the presidential limousine to the White House on Tuesday afternoon, where they and their two daughters watched the grand Inaugural Parade, the 56th of its kind in history with more than 13 000 participants from all 50 US states, from a makeshift roadside reviewing stand.
On their way to the White House, the presidential couple stepped out of their limo twice, walking in the frigid temperatures well below zero and smiling and waving to the ecstatically cheering crowd lining the Pennsylvania Avenue.
Some two million people from all over the world flocked into the US capital to bear witness to the historic inauguration, many of them braving the freezing outdoor cold since dawn just to catch a sight of the new president.
"O-Ba-Ma, O-Ba-Ma," many of them chanted in a concerted loud voice as Mr Obama took to the street.
"Today is a day we look forward to for a long time," said Dean Glenn, an entrepreneur from Virginia. Expressing confidence that Mr Obama will bring changes to the country, he added: "We will have a new spirit of cooperation, hopefully the respect of the world."
"I think he is going to do a magnificent job. He has several teams that would change the nation," said David S. Torain II, who looked on the parade near the Washington Monument that erects at the centre of the National Mall.
However, this head of Mathematics Department of Hampton University seemed not so optimistic about the economy. "It might take a long time to get out of the meltdown. I don't think anybody can turn it around in the next 6 months," he said.
The Tuesday inauguration took place amid unprecedented security. In addition to the Secret Service, it involved 8 000 police officers from the District of Columbia and other jurisdictions, 10 000 National Guard troops, about 1 000 Federal Bureau of Investigation personnel, and hundreds of others from the Department of Homeland Security, the National Park Service and US Capitol Police.
Much of downtown Washington was turned into a pedestrian-only zone by security cordons, and the inaugural parade route was also lined with police and military personnel, who saluted their new commander-in-chief as his limo slowly sailed past.
Shortly before the swearing-in, 66-year-old Joe Biden, a former Delaware senator, took the oath of office as US Vive President, administered by John Paul Stevens, associate justice of the Supreme Court.
Following the inauguration on the US Capitol, Mr Obama's predecessor George W. Bush and his wife Laura boarded a helicopter and headed to the Andrews Air Force Base. The Obama couple, in keeping with the tradition, escorted them to the helicopter and saw them off.
The former president, who concluded his two turbulent terms with record low approval ratings, will fly to Midland, Texas, where he had spent his early years as a child.
