Japan, Australia, and the U.S. have united in stating that any test-launching of an intercontinental missile by North Korea would result in serious and stern consequences.
Reports say Pyongyang has completed fueling a missile with the range to reach the United States, increasing the chances a launch might occur soon.
U.S. officials told Reuters news agency it was difficult to remove fuel from a Taepodong-2 missile, making it appear likely that Pyongyang was serious about the launch.
Since word of a possible test-firing emerged last week, nations around the world have expressed growing concern.
On Monday, Japan's Prime Minister Junichiro Koizumi was the latest leader to say the nation would respond sternly to a missile test by North Korea.
Earlier, Australia's Foreign Minister Alexander Downer warned the North Korean ambassador that "serious consequences would follow such a firing."
"Such action would be highly provocative and would further isolate the DPRK (Democratic People's Republic of Korea," Downer said in a statement issued early Monday.
While North Korea has not commented on any potential missile launch, the official KCNA news agency said in a statement Saturday that alleged sightings of U.S. military surveillance aircraft over the country were creating "an imminent danger of military clash in the sky above those waters."
Some U.S. officials said North Korean leader Kim Jong Il could be bluffing to gain leverage in stalled six-party talks aimed at curbing Pyongyang's nuclear ambitions. The talks include the two Koreas, Russia, the United States, Japan, and China.