US officials confirmed North Korea had fired a long-range rocket Thursday in defiance of international warnings and were checking reports that the launch had ended in failure.
"I can confirm they've carried out a launch," a US official, who spoke on condition of anonymity, said.
A second official said the United States was looking into reports that there had been a 'technical failure', with the rocket disintegerating into the ocean.
Earlier on Friday, North Korea launched a long-range rocket, South Korea's defence ministry and US officials said, with Japan saying that the launch had appeared to have failed.
"North Korea launched a long-range rocket at 07:39 am (2239 GMT Thursday)," a South Korean defence ministry spokesman said.
"US and South Korean intelligence authorities are seeking to determine whether it was a successful launch," he said.
Yonhap news agency also quoted a government source as saying that South Korea was tracking the rocket's trajectory.
Japananese authorities said that the North Korean 'flying object' had fallen into the ocean.
Immediately after the launch, South Korea issued an order urging residents near the inter-Korean border to seek shelter to protect themselves from any debris that might fall from the rocket, Yonhap said.
North Korea has previously said the rocket will place a satellite in orbit for peaceful research purposes, but Western critics see the launch as a thinly veiled ballistic missile test, banned by United Nations resolutions.