US President Barack Obama on Thursday admitted others may be more deserving of the Nobel Peace Prize, but vowed to use the honor to work for world security.
Obama, who has been president for less than 11 months, struck a humble note before receiving the award that puts him alongside the likes of Nelson Mandela, Mother Teresa and Martin Luther King.
"I have no doubt there are others who may be more deserving," Obama said, underlining controversy surrounding the Nobel committee's decision while going on to defend his strategy to escalate the Afghan war.
Norway laid on a day of pageantry for Obama, including an investiture ceremony and a torchlit parade, protected by barricades, helicopters and up to 2,500 police in the country's most elaborate security operation.
Asked about claims he does not merit the award, Obama told a press conference with Norwegian Prime Minister Jens Stoltenberg that he would use the prize to bolster his pro-engagement foreign policy, and to work for lasting world peace.
"The goal is not to win a popularity contest or to get an award, even one as prestigious as the Nobel peace prize. The goal has been to advance America's interests," he said.
"If I am successful in those tasks, then hopefully some of the criticism will subside, but that is not really my concern.
"If I am not successful, then all the praise and the awards in the world won't disguise that fact."
The Nobel committee shocked the world by naming Obama for the prize, but said he had nurtured a new era of engagement and multilateralism in US foreign policy that deserved to be recognised and encouraged.
Obama's first stop after landing in Oslo at dawn was to sign the guest book at the Norwegian Nobel Institute. He wrote seven lines of text which he said congratulated the Nobel committee on work done for the "cause of peace."
He also marveled at how the award of the 1964 Nobel peace prize had galvanized the civil rights fight of Martin Luther King, who he has said helped pave the way for him to become the first African American president.
Obama has admitted the timing of his award is an awkward coincidence, since he last week ordered 30,000 more troops into the Afghanistan war with Taliban insurgents and Al-Qaeda.
He forcibly rejected speculation in Washington that his deadline to begin cutting US troops from Afghanistan in July 2011 would slip.
"Beginning on July 2011 we are beginning to transfer responsibility to the Afghan people and Afghan security forces," Obama said alongside Stoltenberg.
"I have been unambiguous about this so there should not be a debate. Starting in July 2011, we will begin that transition."
Obama lavishly praised Norway's hospitality amid disappointment in Oslo at his decision to contract a traditional three-day pageant into one day.
Referring to an agenda crowded by health care reform, crises on the economy, global warming and Iran's nuclear challenge, he said he had to rush back to Washington.
Disappointment in Norway was mirrored in the United States, where the US leader's once huge popularity has started to fray and isolationist sentiment is on the rise.
Several Norwegian peace and anti-nuclear organisations planned demonstrations outside the award ceremony against a president who took office on a wave of euphoria but who critics say has fallen short of forging promised change.
Outside the Nobel committee offices, protestors held up a banner reading "Obama you won the prize, now earn it."
An InFact institute poll published on Wednesday in the Verdens Gang daily showed just 35.9 percent of Norwegians thought Obama deserved the prize, down from 42.7 percent in October.
Nearly as many, 33.5 percent, believe the 44th US president is unworthy of the award that has been handed out for over a century.
In the United States, a Quinnipiac University survey of 2,313 registered voters published Tuesday showed that by a wide margin of 66-26 percent, Americans think Obama does not deserve the Nobel Peace Prize.
Geir Lundestad, secretary of the Norwegian Nobel Committee, told public radio NRK this week that most US presidents face conflicts and wars -- but the new mood in US foreign policy justified Obama's elevation.
The medicine, physics, chemistry, economics and literature Nobel laureates will receive their awards at a ceremony in Stockholm on Thursday.