North Korea says it is considering postponing a planned long-range rocket launch originally set for between December 10 and 22, citing unspecified problems during preparations.
The Korean Committee for Space Technology said its scientists and engineers were "considering seriously the possibility of readjusting the launch period".
"We are now in the final stage of preparations for the launch", it said in a statement carried by the official Korean Central News Agency.
"But in the course of the preparations, some problems have arisen, compelling our scientists and engineers to consider seriously the possibility of readjusting the launch period."
The committee gave no further details.
A US think-tank, the US-Korea Institute at Johns Hopkins University, said on Friday that preparations for the launch may have been delayed by heavy snow.
North Korea says the launch is to put a satellite into orbit but the United States and its key Asian military allies, South Korea and Japan, insist it is a disguised ballistic missile test that violates UN resolutions triggered by Pyongyang's two nuclear tests in 2006 and 2009.
Japan on Friday ordered its military to shoot down the rocket if it threatens the nation's territory, while Washington put anti-missile destroyers into position, ramping up pressure on Pyongyang.
The USS Benfold and the USS Fitzgerald have been sent to the area to "monitor any potential missile launch by North Korea and to reassure regional allies should a launch occur", a US Navy official told AFP in Washington.
The communist North announced its second long-range rocket launch this year after a much-hyped but botched attempt in April.
Pyongyang-watchers say the December 10-22 launch window is twice the length it was last time, reflecting the difficulties technicians may encounter in the harsh winter weather of the Korean peninsula.
Analysis of satellite imagery suggested preparations at the Sohae satellite launch station were proceeding "more slowly than previously reported", the US-Korea Institute at Johns Hopkins University said.
Washington and Seoul have urged Pyongyang to scrap the launch, while Tokyo has postponed talks originally planned this week with North Korea.
UN diplomats inside and outside the Security Council have reportedly started consultations behind the scenes on what action to take if Pyongyang goes ahead with the launch.
Japan, the United States and South Korea have agreed to demand the UN Security Council boost sanctions on North Korea to levels that match those on Iran, according to the Japanese daily, Asahi Shimbun.
That would include increasing the list of financial institutions, entities and individuals that are subject to asset freezes, the newspaper said.