WASHINGTON - US President Barack Obama declared Monday that a decade of war is ending, the nation's economy is recovering and "America's possibilities are limitless" as he launched into a second term before a flag-waving crowd of hundreds of thousands.
"My fellow Americans, we are made for this moment, and we will seize it, so long as we seize it together," Obama said, moments after taking the oath of office for his second term.
He vowed the US will support global democracy, acting "on behalf of those who long for freedom".
Trumpets blew fanfare and cannons fired as the country watched the president take the oath of office as the world's most powerful elected leader.
Obama's address touched on the broad gifts that bring the country together, and pointed to the work ahead, "the realities of our time."
"We must make the hard choices to reduce the cost of health care and the size of our deficit," he said. But we reject the belief that America must choose between caring for the generation that built this country and investing in the generation that will build its future."
While he was officially sworn in Sunday, as required by law, the glitter of Inauguration Day - the parade down Pennsylvania Avenue toward the White House, the night of balls, the ceremonial beginning of a new four-year presidential term - still enlivened staid Washington. The celebration was pushed to Monday because Jan 20 fell on a Sunday this year. That placed the grand ceremony on the US holiday marking the birthday of revered civil rights leader Martin Luther King.
Obama, the politician who rose improbably from a history as a community organizer in Chicago and a professor of constitutional law to the pinnacle of power, faces a nation riven by partisan disunity, a still-weak economy and an array of challenges abroad.
The president, First Lady Michelle Obama and daughters Sasha and Malia began the day at St. John's Episcopal church, which was built in 1812 and is known as the church of presidents. Obama later had coffee at the White House with congressional leaders, who play major roles in how the country is governed.
Monday's events had less of the effervescence of four years ago, when the 1.8 million people packed into central Washington knew they were witnessing history. Obama is now older, grayer and more entrenched in the politics he once tried rise above. Officials said crowds were about half what they were four years ago.
Obama followed the recent tradition of walking part of the way back to the White House, surrounded by cheers.
As he enters his second term, Americans increasingly see Obama as a strong leader, someone who stands up for his beliefs and is able to get things done, according to a survey by the Pew Research Center for the People & the Press.
The survey shows him with a 52 per cent job approval rating, among the highest rankings since early in his presidency. His personal favourability, 59 per cent, has rebounded from a low of 50 per cent in the 2012 campaign against Republican Mitt Romney.
While Obama convincingly won a second term, the jubilation that surrounded him four years ago is subdued this time around - a reality for second-term presidents. He guided the country through many crushing challenges after taking office in 2009: ending the Iraq war, putting the Afghan war on a course toward US withdrawal and saving the collapsing economy. He won approval for a sweeping health care overhaul.
Yet onerous problems remain, and his success in resolving them will define his place in history.