OSLO — President Barack Obama won the 2009 Nobel Peace Prize today in a stunning decision designed to encourage his initiatives to reduce nuclear arms, ease tensions with the Muslim world and stress diplomacy rather than unilateralism.

Nobel observers were shocked by the unexpected choice so early in the Obama presidency, which began less than two weeks before the Feb. 1 nomination deadline.

White House press secretary Robert Gibbs said Obama woke up to the news a little before 6 a.m. The White House had no immediate comment on the announcement, which took the administration by surprise.

The Norwegian Nobel Committee lauded the change in global mood wrought by Obama's calls for peace and cooperation but recognized initiatives that have yet to bear fruit: reducing the world stock of nuclear arms, easing American conflicts with Muslim nations and strengthening the U.S. role in combating climate change.

"Only very rarely has a person to the same extent as Obama captured the world's attention and given its people hope for a better future," said Thorbjoern Jagland, chairman of the Nobel Committee.

Still, the U.S. remains at war in Iraq and Afghanistan, the U.S. Congress has yet to pass a law reducing carbon emissions and there has been little significant reduction in global nuclear stockpiles since Obama took office.

"So soon? Too early. He has no contribution so far. He is still at an early stage. He is only beginning to act," said former Polish President Lech Walesa, a 1983 Nobel Peace laureate.

"This is probably an encouragement for him to act. Let's see if he perseveres. Let's give him time to act," Walesa said.