The comments came amid international criticism over increasingly close military co-operation between Pyongyang and Moscow, and assertions North Korea sent more than 10,000 troops to Russia to support its invasion of Ukraine.
Previous negotiations with Washington have only highlighted its "aggressive and hostile" policy toward North Korea, Kim said in a speech at a military exhibition in Pyongyang, the capital, the KCNA news agency said.
"Never before have the warring parties on the Korean peninsula faced such a dangerous and acute confrontation that it could escalate into the most destructive thermonuclear war," he said on Thursday.
"We have already gone as far as we can on negotiating with the United States," he said, adding the talks had only shown its aggressive and hostile policy toward North Korea could never change.
North Korean state media have not yet publicly mentioned the re-election of Donald Trump, who held three unprecedented meetings with Kim during his first term, in Singapore, Hanoi, and at the Korean border, in 2018 and 2019.
But their diplomacy yielded no concrete outcome due to the gap between US calls for North Korea to abandon its nuclear weapons and Kim's demands for sanctions relief.
Trump has long touted his ties with Kim, saying in October the two countries would have had "a nuclear war with millions of people killed", but he had stopped it, thanks to his ties with the North's leader.
Photos from the exhibition showed the Hwasong-19 and 18 intercontinental ballistic missiles. (file) (AP PHOTO)
Hong Min, a research fellow at the Korea Institute for National Unification in Seoul, said Kim could be trying to underscore the North's nuclear capabilities before Trump's second term, while leaving the door open for diplomacy.
"He might be suggesting Trump should show his 'willingness to co-exist' before re-opening any talks and calling for a change in the US hostile attitude," Hong said.
Kim also called for developing and upgrading "ultra-modern" versions of weaponry, and vowed to keep advancing defence capabilities to bolster the North's strategic position, KCNA said.
Strategic and tactical weapons were on display at the event, called the Defence Development Exhibition.
KCNA pictures showed the Hwasong-19 and 18 intercontinental ballistic missiles, the Chollima-1 rocket used in a successful satellite launch in November 2023, and the Saetbyol-9 multi-purpose attack drone.
Hong said the pictures also included several weapons needed by or presumed to already have been supplied to Russia for its war in Ukraine, such as 240mm multiple rocket launchers, self-propelled howitzers, anti-tank systems and drones.
North Korea has shipped additional arms to Russia, the South's MPs said on Thursday after being briefed by the national intelligence agency.
Last week, Kim urged the North's military to improve its war-fighting capabilities, blaming the United States and its allies for stoking tension to "the worst phase in history" and calling the Korean peninsula "the world's biggest hotspot".
