Defying warnings from the international community, North Korea launched a long-range rocket on Friday, but it broke apart before escaping the earth's atmosphere and fell into the sea, officials said.

"It flew about a minute, and it flew into the ocean," said Noriyuki Shikata, a spokesman for Japanese Prime Minister Yoshihiko Noda.

He added that Japanese authorities "have not identified any negative impacts, so far," though he said the international ramifications could be significant. "This is something that we think is a regrettable development," he said.

Joseph Cirincione, president of the global security foundation The Ploughshares Fund, told CNN that the launch's apparent failure "shows the weakness of the North Korea missile program" and suggests that the threat from North Korea has been "exaggerated."

"It's a humiliation," he told CNN. "I wouldn't want to be a North Korean rocket scientist today."

In an unusual admission of failure, the North Korean state media announced that the rocket had not managed to put an observation satellite into orbit, which Pyongyang had insisted was the purpose of the launch.

In the past, North Korea has insisted that failed launches have been successful.

"Scientists, technicians and experts are now looking into the cause of the failure," the official Korean Central News Agency said in a report, which was also read out in a news broadcast on state-run television.