Obama Inaugurated

Those gathered in freezing temperatures around the capitol building erupted in applause as Obama took the oath of office and became the 44th president of the US.

During the swearing-in, he used his full name, Barack Hussein Obama, an open gesture of recognition of his Muslim father, who was Kenyan, and a facet of his background that was underplayed during his election campaign against Republican John McCain.

Obama laid his hand on a Bible used in 1861 by president Abraham Lincoln, the Civil War president who freed the slaves. Lincoln's 200th birthday is being celebrated this year and has formed a keystone of the inaugural theme.

Standing nearby was outgoing president George W. Bush, who leaves office as one of the most unpopular presidents in recent times. When he walked out on the stage, a loud boo went up from the crowd.

Crisis mode

In a speech after his swearing in, Obama acknowledged the historical nature of the day, but also laid out the very real current crises facing the United States.

"Today I say to you that the challenges we face are real," he said in the inaugural speech. "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."

Obama mentioned that the US was experiencing its worst economic conditions in 70 years and that the US involvement in wars in Afghanistan and Iraq had placed the country in the "midst of crisis."

"On this day, we gather because we have chosen hope over fear, unity of purpose over conflict and discord," he said.

Obama takes office amid high expectations that he can turn around the economy that shed more than one million jobs last year and is bogged down in the worst recession since the Great Depression of the 1930s. Obama inherits two wars and a bruised US image in the world after eight years of the Bush presidency.

"Starting today, we must pick ourselves up, dust ourselves off, and begin again the work of remaking America," Obama said.

In a message meant for the Muslim world, Obama said he would seek a "new way forward" based on mutual interest and respect.

But he added: "we will not apologize for our way of life, nor will we waver in its defense, and for those who seek to advanced 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."

Quick action

Obama has already begun consulting with members of Congress on a $825-billion stimulus plan to boost the economy by investing in infrastructure projects, developing alternative energy and other projects to get people back to work.

Among the first acts Obama is expected to take is ordering the closure the Guantanamo detention center at the US Navy base in Cuba for holding suspects in the war on terrorism. The prison, where most of the remaining detainees have been held for years without charges, has tarnished America's standing in the world. Obama has cautioned that the actual closure could take months or as long as a year.

He has pledged to overhaul rules on Wall Street. In his speech, he praised the ability of

markets to create wealth and spur freedom but insisted that careful oversight was also crucial.

The new president also listed reform of the health care and education systems and action to tackle climate change as among his top domestic priorities.

Obama will spend Tuesday evening attending various black tie inaugural balls throughout the city, then will get down to the nation's business during his first full day of office on Wednesday,

when he will meet with his top economic advisers.

On Thursday, Obama is expected to meet with General Ray Odierno, the top commander in Iraq, and General David Petraeus, chief of US Central Command, which oversees military operations in the Middle East, South Asia and parts of Africa, CNN reported.

Exit Bush

Former president George W Bush boarded a helicopter behind Capitol Hill on Tuesday to depart from Washington and return to civilian life.

Obama and his wife Michelle, along with Vice President Joe Biden and wife Jill, said goodbye to Bush and wife Laura on the east side of the US Congress building.

The Bushes are first headed to Midland, Texas, for a homecoming celebration in the city that hosted a send-off for them eight years ago. Then they'll go to their ranch in Crawford, near Waco, for their first night as private citizens again.