SEOUL, South Korea (AP) -- North Korea held off launching a long-range rocket Monday, the first day of a 13-day window during a frigid, snowy stretch of winter weather, a day after announcing it may delay the controversial liftoff.
Pyongyang had made a surprise announcement earlier this month that it would launch a rocket mounted with a satellite one morning between Monday and Dec. 22, its second attempt this year. The North Koreans called it a peaceful bid to advance its space program, and a last wish of late leader Kim Jong Il.
However, the U.S., Japan and other nations see it as an illicit test of missile technology, and have warned North Korea to cancel the launch -- or face a new wave of sanctions.
There was no indication that the launch at a west coast site in North Korea's northwest took place Monday, South Korean officials said. Experts in Seoul and Tokyo speculated that technical glitches may have forced scientists to postpone the launch of the finicky three-stage rocket, its fourth attempt since 1998.
Early Sunday, a spokesman from North Korea's Korean Committee for Space Technology told state-run media that scientists were considering "readjusting" the timing of the launch. He did not elaborate.
Temperatures in the nearby border city of Sinuiju, 35 miles (50 kilometers) to the north, dropped to minus-13 C (8.6 F) during the launch window, and the Korean Peninsula has been seized by early winter storms and unusually cold weather, the Korean Meterological Agency said in Seoul.
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.
Snow covered the site last week, according to commercial satellite imagery taken by GeoEye on Dec. 4 and shared with The Associated Press by the 38 North and North Korea Tech websites. The road from the main assembly building to the launch pad showed no fresh tracks, indicating that the snowfall may have stalled the preparations.
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," Defense Minister Satoshi Morimoto told reporters Monday. "We have not seen any objective indication that would cause us to make any change to our preparedness."
In addition to three failed launches, North Korea has unveiled missiles designed to target U.S. soil and has tested two atomic bombs in recent years. It has not yet proven to have mastered the technology for mounting a nuclear warhead to a long-range missile.
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.
The announcement of a North Korean rocket launch also sparked concern in regional capitals due to 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.
Last week, U.S. Secretary of State Hillary Rodham Clinton said Washington was deeply concerned, and urged foreign ministers from NATO and Russia to demand that Pyongyang cancel its plans. Moscow joined calls on Pyongyang to reconsider.
China, North Korea's main ally and aid provider, also noted its concern, acknowledging North Korea's right to develop its space program but urging Pyongyang to harmonize the bid with restrictions -- including those set by the U.N. Security Council.
North Korea, however, may have its own reasons for launching a rocket in snowy December. The country will be marking the first anniversary on Dec. 17 of the 2011 death of Kim Jong Il.
However, 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 Defense 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 contributed to this report from Tokyo.
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