The United States said it was ready for any scenario after North Korea threatened a pre-emptive attack and suggested it was poised to restart an atomic reactor.
But as Washington warned Pyongyang it was only isolating itself, there were signs the United States was moving toward talks over the second nuclear crisis provoked by the communist state in a decade.
North Korea's state media kept up a stream of alarmist statements today after a senior diplomat told British reporters in Pyongyang that "pre-emptive attacks are not the exclusive right of the US".
Pyongyang portrayed US contingency plans to beef up forces in the western Pacific during any Iraq hostilities as actual deployments that foreshadowed an attack.
"If the US moves to bolster aggression troops are unchecked, the whole land of Korea will be reduced to ashes and the Koreans will not escape horrible nuclear disasters," said the Committee for the Peaceful Reunification of the Fatherland.
Those dire warnings followed a statement from the energy-starved country's foreign ministry Wednesday, indicating it was preparing to fire up a reactor it is thought to have used in the past to produce plutonium for weapons.
Washington said the developments were dangerous but no reason to abandon diplomacy to resolve the four-month-old crisis.
North Korea, however, insists the nuclear issue can only be settled in direct talks with the United States.
Washington says it is willing to talk to Pyongyang about dismantling nuclear programmes that include a uranium-0enrichment plant and a nuclear complex capable of producing plutonium.