Updated at 7:22 a.m. Eastern.
Barack Obama on Thursday acknowledged the irony of being a wartime president honored for peace, saying that criticism of his Nobel Prize as premature might recede if he advances goals such as a nuclear-free world and tackling climate change.
But, he added, proving doubters wrong is "not really my concern."
"If I'm not successful, then all the praise in the world won't disguise that fact," the U.S. president said from this Nordic capital where he is picking up his Nobel Peace Prize.
The Nobel committee announced Obama had won the peace prize in October when he wasn't even nine months on the job, recognizing his aspirations to reshape the way the U.S. deals with the world much more than his actual achievements.
"It was a great surprise to me," Obama said after meeting with Norwegian Prime Minister Jens Stoltenberg. "I have no doubt that there are others who may be more deserving."
CBS News chief White House correspondent Chip Reid, traveling with the president, reports that it's still unclear whether becoming a Nobel laureate will help Mr. Obama or hurt him at home.
Just days before coming here to formally accept the Nobel, Obama announced that he is ordering 30,000 more U.S. troops into war in Afghanistan.
Debate over that continued in Norway, where he spent much of a brief pre-ceremony news conference explaining his decision, reports Reid. Mr. Obama said the July 2011 date he set for the U.S. withdrawal from Afghanistan to begin but that the pace of the full withdrawal will be gradual and condition-based.
"We're not going to see some sharp cliff, some precipitous drawdown," Obama said.
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Speaking Thursday to "Early Show" co-anchor Harry Smith, former Press Secretary to President Bill Clinton, Dee Dee Myers, said Mr. Obama would likely use his speech to "talk about how the definition of peace and security needs to be broader." She said Mr. Obama would have to convince Americans and the rest of the world that sometimes peace requires a fight.
Dan Bartlett, a former senior counselor to President George W. Bush, agreed with that assessment, telling Smith Mr. Obama's best option was to project to the world that "peace comes through strength."
Bartlett acknowledged, however, that the message would probably go down better with Mr. Obama's conservative opponents and independent voters in America than with his more liberally-minded base and international supporters.
For their part, peace activists staged a protest to coincide with the Nobel ceremonies.
The president's motorcade arrived at Oslo's high-rise government complex to a few dozen anti-war protesters gathered behind wire fences nearby. Dressed in black hoods and waving banners, the demonstrators banged drums and chanted anti-war slogans.
"The Afghan people are paying the price," some shouted.
Greenpeace and anti-war activists planned larger demonstrations later. Protesters have plastered posters around the city, featuring an Obama campaign poster altered with skepticism to say, "Change?"
Stoltenberg defended Obama as a Nobel laureate.
"I cannot think about anyone else who has done more for peace during the last year than Barack Obama," Stoltenberg said at Obama's side. "I think it's a very bold and important decision."
In awarding the prize to Obama, the Nobel panel cited his call for a world free of nuclear weapons, for a more engaged U.S. role in combating global warming, for his support of the United Nations and multilateral diplomacy and for broadly capturing the attention of the world and giving its people "hope."
The list of Nobel peace laureates over the last 100 years includes transformative figures and giants on the world stage. They include heroes of the president, such as the Rev. Martin Luther King Jr., Nelson Mandela and others he has long admired, like George Marshall, who launched a postwar recovery plan for Europe.
So the choice of Obama was such a surprise, and derided so loudly by some critics as premature, that the Nobel committee took the unusual step of defending itself. Obama seemed to try to distance himself from that debate.
"On a whole host of initiatives that I've put forward this year, some of which are beginning to bear fruit, the goal is not to win a popularity contest or to win an award even one as esteemed as the Nobel Peace Prize," he said. "The goal is to advance American interests."
Obama's Nobel speech a tradition billed as the winner's lecture for the world will explore his thinking about war, security and the pursuit of peace. He is likely to spell out the role of American leadership and the responsibilities of all nations.
Obama's first stop in Oslo was the Norwegian Nobel Institute, where the Nobel committee meets to decide who gets the prestigious prize.
After signing the guest book at the Institute, Obama told reporters he had penned thanks to the committee members and noted the pictures of former winners filling the wall, saying that many gave "voice to the voiceless."
In the evening, Obama is expected to wave to a torchlight procession from his hotel balcony and stroll with Norwegian royalty to a dinner banquet. He will offer comments a second time there and cap his brisk jaunt to Europe.
The president and his wife, Michelle, arrived here in the morning after an overnight flight from Washington, coming off Air Force One holding hands and smiling. Obama was due back in Washington by midday Friday skipping the second day of Nobel festivities.
Obama's quick stopover miffed some in Norway, but reflects a White House that sees little value in trumpeting an honor for peace so soon after Obama announced he was sending more troops off to war.
Asked if Obama was excited about the award, national security aide and speechwriter Ben Rhodes responded, "I think he feels as if it places a responsibility upon him."
"It's the company that you keep as a Nobel laureate that I think makes the deepest impression upon him," said Rhodes, who was helping craft the president's speech. "That kind of adds an extra obligation to essentially extend the legacy."
The Nobel honor comes with a $1.4 million prize. The White House says Obama will give that to charities but has not yet decided which ones.