Accepting the Nobel Peace Prize in Oslo on Thursday, President Obama acknowledged the "considerable controversy" over the award.
"In part, this is because I am at the beginning, and not the end, of my labors on the world stage," Obama said. "Compared to some of the giants of history who have received this prize - Schweitzer and King, Marshall and Mandela - my accomplishments are slight.
"And then there are the men and women around the world who have been jailed and beaten in the pursuit of justice; those who toil in humanitarian organizations to relieve suffering; the unrecognized millions whose quiet acts of courage and compassion inspire even the most hardened of cynics. I cannot argue with those who find these men and women - some known, some obscure to all but those they help - to be far more deserving of this honor than I.
"But perhaps the most profound issue surrounding my receipt of this prize is the fact that I am the commander in chief of a nation in the midst of two wars," he said.
While one of these wars, in Iraq, "is winding down," as Obama put it, he faced the difficult task of accepting the peace prize just a week after announcing he is sending 30,000 more troops to Afghanistan.
Yet many world figures pointed to Obama's break with the aggressive confrontationalism of the Bush era as the reason for the award. Citing Obama's turn to diplomacy and his push for nuclear disarmament, they said the prize signaled the world's strong desire for the U.S. to continue in that direction.
United Nations Secretary-General Ban Ki-Moon said, "We are entering an era of renewed multilateralism - a new era. He embodies that new spirit of dialogue and engagement."
The head of Norway's Nobel Peace Prize committee, Thorbjeorn Jaglund, told reporters the committee had awarded the prize to Obama for "contributing to improve the international climate, strengthen international bodies such as the UN." The Nobel committee, Jaglund said, "wants to enhance that kind of international policy."
South African Archbishop Desmond Tutu, a 1994 Nobel Peace Prize winner, noted that Obama "has reached out an open hand to the Arab world, to Iran, and also to North Korea."
On the streets of Soweto, South Africa, one man told the BBC, "We are really proud of him because he's Black, he's an African American. In that way it is a recognition of how we as humanity can work together to achieve bigger things."
Another Sowetan saw a link between Obama, Tutu and Nelson Mandela, another Peace Prize recipient. "They're all African brothers," the man said. "I'm so happy that peace can come from Africa."
Obama's speech tried to span "two seemingly irreconcilable truths." On one hand, "the instruments of war do have a role to play in preserving the peace," he argued. "And yet this truth must coexist with another - that no matter how justified, war promises human tragedy."
He presented a wide-ranging discussion of the history of war, the concept of "just war," the advent of the nuclear age, the rise of terrorism, and the increasing toll on civilians.
"Wars between armies gave way to wars between nations - total wars in which the distinction between combatant and civilian became blurred," he said.
"Moreover, wars between nations have increasingly given way to wars within nations. The resurgence of ethnic or sectarian conflicts, the growth of secessionist movements, insurgencies and failed states have increasingly trapped civilians in unending chaos. In today's wars, many more civilians are killed than soldiers; the seeds of future conflict are sown, economies are wrecked, civil societies torn asunder, refugees amassed and children scarred."
Paying tribute to the moral force of nonviolence, Obama cited Martin Luther King's statement, "Violence never brings permanent peace. It solves no social problem: It merely creates new and more complicated ones."
"As someone who stands here as a direct consequence of Dr. King's life's work, I am living testimony to the moral force of non-violence," he said. "I know there is nothing weak, nothing passive, nothing naive in the creed and lives of Gandhi and King."
But arguing in defense of his Afghanistan surge, Obama said, "I face the world as it is, and cannot stand idle in the face of threats to the American people." He linked the Afghanistan war to the U.S. Cold War role of helping "underwrite global security for more than six decades with the blood of our citizens and the strength of our arms."
At the same time, he emphasized the linkage of peace and justice, human rights, and the human striving for these things.
"A just peace includes not only civil and political rights - it must encompass economic security and opportunity," he said. "Neither America's interests - nor the worlds - are served by the denial of human aspirations."
A commentary on the Chinese news agency web site Xinhuanet pointed to the challenges the award presents Obama with. The article was headlined, "Greater responsibility for Nobel ‘wartime president'."
Noting the controversy over awarding Obama the Nobel even as he sends more troops to Afghanistan, the commentary seemed to be telling Obama that China has concerns over that policy, and is expecting him to live up to the prize.
"People may have different reasons for challenging Obama's award, but one thing is certain," the Xinhua article said. "The peace prize brings with it greater responsibility both for the president and the United States to contribute more to world peace."
How long will U.S. troops remain in Iraq and Afghanistan, how quickly will the Guantanamo prison be closed, and especially how strongly will the U.S. lead on climate change, the article asked. It concluded, "The world not only expects an oral commitment from the Obama administration, it also looks forward to seeing him translate his promises into action. There is a lot Obama and his country can and should do to live up to the expectations of the international community."