SEOUL, South Korea - North Korea is pressing ahead with preparation for a long-range rocket launch after extending its liftoff window by another week until Dec. 29 because of technical problems.
It's North Korea's second attempt this year, and the fifth since 1998, to launch a rocket that the United Nations, Washington, Seoul and others call a cover meant to test technology for missiles that could be used to strike the United States. They have warned North Korea to cancel the launch or face more sanctions.
The North Koreans call the launch a peaceful bid to advance their space program and a last wish of late leader Kim Jong Il, who died on Dec. 17 last year. North Korea is also celebrating the centennial this year of the birth of national founder Kim Il Sung, current leader Kim Jong Un's grandfather. The rocket it launched in April broke apart seconds after liftoff.
On Monday, an unidentified spokesman for the North's Korean Committee of Space Technology told state media that scientists found a "technical deficiency in the first-stage control engine module of the rocket." The statement didn't elaborate but said technicians were moving ahead with final preparations for the liftoff from a west coast launch site.
The second day of North Korea's extended 20-day launch window began on Tuesday morning without signs of a liftoff. The specifics of the rocket's technical problems aren't clear, but state media put out an overnight dispatch detailing the unusually cold weather and heavy snow hitting the northern part of the Korean Peninsula.
The announcement of the planned rocket launch has sparked worry because of the timing: South Korea and Japan hold key elections this month, President Barack Obama begins his second term in January, and China has just formed a new leadership.
The North had originally set up a 13-day launch window, starting Monday, but it announced early Sunday that it may delay the liftoff because of unspecified reasons.
U.S. State Department spokeswoman Victoria Nuland said Monday that as far as the United States can tell it's simply a delay and North Korea still plans to launch the rocket. She reiterated Washington's demand that the North comply with U.N. Security Council resolutions and not proceed with the launch.
She said Secretary of State Hillary Rodham Clinton spoke Friday with Chinese Foreign Minister Yang Jiechi about what influence China could bring to bear on the North "to see reason and focus on the development of their country and the feeding of their people rather than on ballistic missile launches." China is North Korea's only major ally.
North Korea said Monday that it has faced exceptionally cold weather since last week and that most areas received heavy snow on Wednesday. State media quoted Ri Chol Su, vice-director of the North's Central Meteorological Institute, as saying the temperature in western coastal areas, where the rocket launch pad is located, dropped to up to minus-17 C (1.4 F) from Saturday to Monday.
Engineers can launch a rocket when it's snowing, but lightning, strong wind and freezing temperatures have the potential to stall liftoff, said Lee Chang-jin, an aerospace professor at Seoul's Konkuk University.
Still, Japanese Prime Minister Yoshihiko Noda said Monday that his government would maintain vigilance. Tokyo has mobilized its military to intercept any debris from the rocket.
"At this moment, we are keeping our guard up," Defence Minister Satoshi Morimoto told reporters Monday. "We have not seen any objective indication that would cause us to make any change to our preparedness."
At least one Aegis-equipped South Korean destroyer has been deployed in the Yellow Sea to monitor North Korea's rocket launch, according to South Korean officials.
The United States has also moved extra ships with ballistic missile defence capabilities toward the region, officials said.
The U.S., Japan and South Korea say they'll seek U.N. Security Council action if the launch goes ahead in defiance of existing resolutions. The council condemned April's launch and ordered seizure of assets of three North Korean state companies linked to financing, exporting and procuring weapons and missile technology.
In addition to four previous launches, North Korea has unveiled missiles designed to target U.S. soil and has tested two atomic devices in recent years. It has not yet proven to have mastered the technology for mounting a nuclear warhead to a long-range missile, however.
A successful launch would mean North Korea could develop an intercontinental ballistic missile capable of striking the U.S. mainland within two to three years, said Chong Chol-Ho, a weapons of mass destruction expert at the private Sejong Institute near Seoul.
Six-nation negotiations to offer North Korea much-needed aid in exchange for nuclear disarmament have been stalled since early 2009.
International pressure and the prospect of dialogue may be a factor in the delay, analysts in Seoul said.
China must have sent a "very strong" message calling for the North to cancel the launch plans, said analyst Baek Seung-joo of the South Korean state-run Korea Institute for Defence Analyses.
North Korea may also be holding off if the U.S., its longtime Korean War foe, actively engages Pyongyang in dialogue, said Koh Yu-hwan, a professor of North Korean studies at Seoul's Dongguk University.
Associated Press writer Mari Yamaguchi in Tokyo and Matthew Pennington in Washington contributed to this report.