WASHINGTON President Barack Obama faces a test of tone and political dexterity on Thursday, when he accepts the Nobel peace prize days after escalating a war and with a resume lacking defining foreign policy wins.

Obama's trip to Oslo calls for a steady diplomatic touch, as he addresses divergent audiences around the world and in the United States where isolationist sentiment is on the rise.

He is a war president who last week ordered the deployment of 30,000 more men to Afghanistan to intensify the war against Al Qaeda and the Taliban - yet he is accepting a revered peace prize - a scenario even the White House admits is puzzling.

“We'll address directly the notion, I think, that many have wondered, which is the juxtaposition of the timing for the Nobel Peace Prize and his commitment to add more troops into Afghanistan,” said Obama's spokesman Robert Gibbs.

Asked whether Obama would accept the prize as a “war president,” Gibbs replied “Exactly.”

No one was more surprised than Obama when he was woken one morning in October with the shock news that he was a Nobel laureate.

He had been in office for just over nine months, with his pro-engagement foreign policy evolving and still lacking a major success story.

Many Americans, and even some Obama supporters abroad, appear to doubt that the president deserves a prize awarded in the past to Nelson Mandela, the Dalai Lama and Aung San Suu Kyi.

Obama's humble tone after the announcement may offer hints of how he will approach the Nobel lecture on Thursday.

“To be honest, I do not feel that I deserve to be in the company of so many of the transformative figures who've been honoured by this prize,” Obama said on October 9.

“Let me be clear I do not view it as a recognition of my own accomplishments, but rather as an affirmation of American leadership on behalf of aspirations held by people in all nations.”

It is ironic that Obama's apparent success in rebranding the United States to the rest of the world comes as Americans, weary of years of war and brewing international crises, seem to be turning inward.

The president appears to revel in engagement with foreigners, stressing his Kenyan heritage, childhood years growing up in Indonesia and calling himself America's first Pacific president.

But a new poll of Americans last week showed that 49 per cent of those asked agreed that the United States should mind its own business abroad and 44 per cent disagreed.

It was the first time since the Pew Research Centre had began the survey 45 years ago that isolationist sentiment had come out on top.

Like Obama, the Nobel committee had to defend itself over the prize, arguing that it is intended to spur the president to future greatness rather than a recognition of a complete legacy.

The committee lauded Obama for “extraordinary efforts to strengthen international diplomacy and cooperation between peoples.”

“The committee has attached special importance to Obama's vision of and work for a world without nuclear weapons,” and the president was credited with creating a “new climate” of multilateral diplomacy in international politics.

But US cynics accused the Nobel committee of picking Obama simply because he was not his unpopular predecessor George W. Bush.

They also charge that his vaunted engagement policy has yet to show results and the award emboldened those who argue Obama is notable more for polished performance and soaring rhetoric than results.

Obama advocates however counter that he is driving towards a new treaty on nuclear arms cuts with Russia, and offered to rebuild US ties with Islam in a major speech to the Muslim world.

He also offered an open hand to Iran, which appears to have been spurned, is engaging North Korea and Myanmar and transformed US policy on global warming.

Geir Lundestad, secretary of the Norwegian Nobel committee, said on Norwegian NRK radio that most American presidents face conflicts and wars - but the new mood in US foreign policy justified Obama's elevation.

The president had “put the accent on international cooperation, the United Nations, dialogue, negotiation, the struggle against climate change and disarmament,” Lundestad said.

Obama is the third sitting US president to win the peace prize, after Theodore Roosevelt in 1906 and Woodrow Wilson in 1919.—AFP