Japan's foreign minister and the U.S. ambassador in Tokyo held a 30-minute meeting late Saturday to discuss what actions their governments would likely take, if North Korea test fires a ballistic missile.
Japanese and South Korea media report that liquid fuel tanks have been observed at a North Korean site and booster rockets are on the launch pad.
For more than a week, Japanese and U.S. government officials have expressed increasing concern that the communist state is readying a launch of a Taepodong-2 long-range ballistic missile. Published reports in Tokyo and Seoul say a launch could come as early as Sunday.
U.S. Ambassador Thomas Schieffer, following his Saturday night meeting with Japan's foreign minister, told reporters there are indeed indications Pyongyang is preparing to launch an intercontinental ballistic missile.
"We hope that the North Koreans will not take this provocative action," he said. "It will only isolate the North Koreans further from the rest of the internationalcommunity."
The ambassador added that, if North Korea does launch the missile, all options are on the table a reference to the possibility of sanctions being imposed on Pyongyang.
North Korea has previously said it would consider any sanctions imposed by Japan tantamount to a declaration of war.
Japanese Foreign Minister Taro Aso said both Washington and Tokyo are urgently trying to convey to Pyongyang that it must back away from a launch.
Aso says Tokyo is relaying its concerns through Chinese diplomats, while the United States is using the "New York channel," a reference to communication with North Korea's diplomats at the United Nations. Neither Japan nor the United States has diplomatic relations with North Korea.
If North Korea launches a missile, that would end a seven-year moratorium on long-range testing that North Korea imposed on itself.
Analysts say North Korea, in an effort to dispel international condemnation, may claim that the launch of the three-stage rocket is to deploy a satellite. It made a similar statement after its 1998 missile test, but U.S. intelligence agencies and other space watchers say no such satellite made it into orbit.