North Korean leader Kim Jong-un said the United States is his nation's "biggest enemy" and plans for a nuclear-powered submarine are complete, state media reported on Saturday, in comments that throw down the diplomatic gauntlet to the incoming administration of Joe Biden.
The declaration comes less than two weeks ahead of the new US president's inauguration and after a tumultuous relationship between Mr Kim and the outgoing leader Donald Trump.
Mr Kim and Mr Trump first engaged in a war of words and mutual threats, before an extraordinary diplomatic bromance that featured headline-grabbing summits and declarations of love by the US president.
But little substantive progress was made, with the process deadlocked after their February 2019 meeting in Hanoi broke down over sanctions relief and what Pyongyang would be willing to give up in return.
The North "should focus and be developed on subverting the US, the biggest obstacle for our revolution and our biggest enemy", Mr Kim told the five-yearly congress of the ruling Workers' Party of Korea, the official KCNA news agency reported.
"No matter who is in power, the true nature of its policy against North Korea will never change," it quoted him as saying, without mentioning Mr Biden by name.
The comments will be seen as a declaration of defiance aimed at the new US administration.
The change of leadership in Washington presents a challenge for Pyongyang, which has previously called Mr Biden a "rabid dog", while he characterised Mr Kim as a "thug" during the presidential debates.
The US is expected to return to more orthodox diplomatic approaches under Mr Biden, such as insisting on extensive progress at working-level talks before any leaders' summit can be considered.
The process with Mr Trump was brokered by South Korean President Moon Jae-in, but Mr Kim said Seoul was in breach of inter-Korean agreements and "and disregarding our warnings that it should stop joint military drills with the US".
Strategic balance
Pyongyang has poured vast amounts of resources into developing its nuclear weapons and ballistic missiles, which it says it needs to defend itself against a possible US invasion.
The programs have made rapid progress under Mr Kim, including by far its most powerful nuclear blast to date and missiles capable of reaching the entire continental US, at a cost of increasingly stringent international sanctions.
At a military parade in October, it showed off a huge new missile that analysts concurred was the largest road-mobile, liquid-fuelled missile anywhere in the world, and was highly likely to be designed to carry multiple warheads in independent re-entry vehicles (MIRVs).
Kim Jong-un speaking during the 8th Congress of the Workers' Part of Korea opening ceremony in Pyongyang, 5 January 2021 Source: KCNA
The North has also completed plans for a nuclear-powered submarine, Mr Kim has revealed - something that would change the strategic balance.
Such a weapon, if it was built and went into service, could enable Pyongyang to surreptitiously bring its missiles close to the United States, cutting down warning times ahead of any launch.
Designs for the vessel were "in the stage of final examination", Mr Kim said.
The country should "further advance nuclear technology" and develop small-sized, lightweight nuclear warheads "to be applied differently depending on target subjects", he added.
The comments came in Mr Kim's nine-hour work report to the congress, spread over three days, which KCNA was reporting in detail for the first time.
The congress is the top ruling party gathering, a grand political set-piece that reinforces the regime's authority and can serve as a platform for announcements of policy shifts or elite personnel changes.
