North Korea on Wednesday ruled out resuming dialogue with the "gangster-like" United States, and vowed to respond to any US aggression with nuclear strikes and cyber warfare.
The bellicose statement from the country's top military body, the National Defence Commission (NDC), came after reported moves by Washington and Pyongyang to revive long-stalled six-nation talks on denuclearisation.
It also preceded the start in early March of annual joint US-South Korea military exercises that always presage a sharp spike in military tensions and rhetoric on the divided peninsula.
The NDC statement was an apparent reaction to remarks Barack Obama made regarding the eventual collapse of the regime in North Korea, which the US president called the "most cut-off nation on Earth".
The NDC statement, which labelled the Obama administration a mud-slinging "cesspool," said the president's comments amounted to a threat to engineer the country's downfall.
"Since the gangster-like US imperialists are blaring that they will 'bring down' the DPRK (North Korea)... the army and people of the DPRK cannot but officially notify the Obama administration... that the DPRK has neither need nor willingness to sit at negotiating table with the US any longer," the NDC said.
-- Nuclear or cyber war --
The statement, carried by the North's official KCNA news agency and titled "US imperialists will face final doom," said North Korea would respond to any US military aggression in kind -- whether with conventional, nuclear or cyber forces.
Obama slapped sanctions on North Korea last month following the hacking of Hollywood studio Sony Pictures' computer network.
US officials blamed the attack on Pyongyang and described it as the most damaging commercial hack in US history.
North Korea, which is known to have built up a formidable cyber warfare unit, has officially denied any involvement.
The Washington Post reported on Monday that US and North Korean nuclear envoys had been secretly discussing the idea of "talks about talks", but had been unable to agree on practical arrangements.
State Department spokeswoman Jen Psaki stressed the US had not changed its position of requiring the North to take tangible steps towards denuclearisation before any meaningful dialogue can be held.
North Korea carried out nuclear tests in 2006, 2009 and 2013.
The aim of the six-party talks is to persuade the North to scrap its nuclear weapons in return for aid and other incentives such as security guarantees and diplomatic normalisation.
Last month, North Korea offered to suspend future nuclear tests temporarily if Washington cancels its annual military drills with the South.
The proposal was formally rejected by the US as an "implicit threat."
-- 'Final ruin' of US --
Pyongyang views the joint exercises as provocative rehearsals for invasions, while Seoul and Washington insist they are purely defensive in nature.
The NDC statement said the North was capable of bringing about the "final ruin of the US" with its "precision and diversified nuclear striking means."
Hong Hyun-Ik, a senior researcher at the Sejong Institute think-tank in Seoul, said neither North Korea nor the United States appeared particularly sincere about the idea of dialogue.
The United States needs a "trouble-making" North Korea" to rally support from its allies for its ultimate strategy of keeping China's growing influence in check in the region, Hong said.
At the same time, with its economy in better shape than the past, North Korea feels "no sense of urgency" about resuming talks.
"Against this backdrop, neither North Korea nor the United States wants to take the initiative for a breakthrough," Hong said.