The UN Security Council is expected to discuss on Wednesday North Korea's threat to conduct its first underground nuclear test amid demands by the United States for a "robust" reaction from the world body on the issue.
The United States demanded a robust Council reaction to the threat with its UN Ambassador John Bolton describing it as a "grave threat" to international peace and security. But other ambassadors were taking more cautious approach.
"Obviously the ballistic missiles, if mated with nuclear weapons, would be a very grave threat to international peace and security," Bolton said.
Ambassadors from other Council members also expressed their concern over the development but said that they need to discuss the issue.
The announcement sent shock waves across the world with almost every country condemning the move but it was uncertain what the Council could do if North Korea decides to go ahead.
Analysts and diplomats at the United Nations said the test, if conducted, would have far reaching repercussions in the region and could set off an armed race and force Japan and South Korea reconsider their nuclear options.
Current month's Council President Ambassador Kenzo Oshima of Japan said such a test would cause serious threat to regional and international peace and security and would, moreover, constitute a grave challenge to non-proliferation.
The Council had imposed weapon-related sanctions on North Korea after it carried out several missile tests in July.
The resolution had asked North Korea to suspend all activities on its ballistic missile programmes.
Despite sharp reactions, diplomats were not sure what exactly the Council could do.
The Japanese ambassador denied rumours that his country has circulated a draft statement on the North Korean threat and said the members would decide what the appropriate reaction could be.
Diplomats said the Council is likely to seek the resumption of six-party talks to which the North might not be averse.
American intelligence officials were quoted as saying that they saw no signs that a test was imminent.
But they cautioned that two weeks ago, American officials who have reviewed recent intelligence reports said American spy satellites had picked up evidence of indeterminate activity around North Korea's main suspected test site.
It was unclear to them whether that was part of preparations for a test, or perhaps a feint related to the visit at that time to Washington of South Korea's president, Roh Moo Hyun.
Diplomats also say that the announcement was perhaps aimed at grabbing attention at a time when South Korea was getting attention on the imminent selection of its candidate Ban Ki-Moon as the next United Nations Secretary-General.
The American intelligence agencies believe that North Korea has enough fuel to produce six to eight weapons.