Japan said Monday it was on full alert over North Korea's planned rocket launch as a 13-day lift-off window opened, despite a suggestion from Pyongyang that it could delay the much-criticised move.
North Korea said Sunday that the launch, originally scheduled for December 10-22, could be changed "for some reasons", giving no further details.
South Korea's Yonhap news agency, citing a government official in Seoul, later said the North had stopped all preparations at the launch site in the country's northwest.
Japan has deployed missile defence systems to intercept and destroy the rocket if it looks set to fall on its territory.
"We are taking all possible measures for vigilance," Prime Minister Yoshihiko Noda told reporters as he entered his office on Monday before the launch window opened at 7:00 am (2200 GMT Sunday).
Defence Minister Satoshi Morimoto said Tokyo would keep a close eye on developments despite the comments from North Korea.
"We don't think enough changes are occurring to change our posture," he said. "We will maintain our current posture unless North Korea issues a formal notice or announcement" on the delay, he said.
Analysts said technical problems or snow, rather than overseas political pressure, are likely to be behind the delay in what the North calls a satellite launch.
The impoverished but nuclear-armed nation insists the long-range rocket launch -- its second this year after a much-hyped but botched mission in April -- is for peaceful scientific purposes.
But the United States, and allies South Korea and Japan, say Pyongyang plans a disguised ballistic missile test that violates UN resolutions triggered by its two nuclear tests in 2006 and 2009.
A North Korean Unha-3 rocket is shown at the Tangachai-ri space centre in April 2012. Japan said Monday it was on full alert over North Korea's planned rocket launch as a 13-day lift-off window opened, despite a suggestion from Pyongyang that it could delay the much-criticised move.
Graphic showing the Sohae satellite launch station in North Korea. Japan said Monday it was on full alert over North Korea's planned rocket launch as a 13-day lift-off window opened, despite a suggestion from Pyongyang that it could delay the much-criticised move.
