North Korea has said it may pull out of a summit with US President Donald Trump if the US insists it gives up its nuclear weapons.
The highly anticipated meeting between Mr Trump and North Korea’s Kim Jong-un is due to take place on 12 June.
But in an angry statement, North Korea’s vice-foreign minister accused the US of making reckless statements and of harbouring sinister intentions.
He pointed the finger squarely at US National Security Adviser John Bolton.
“We do not hide our feeling of repugnance towards him,” Kim Kye-gwan said.
The groundbreaking agreement for Mr Kim and Mr Trump to meet came about as North Korea said it was committed to denuclearising the Korean peninsula.
Exactly what that would entail has remained unclear, but North Korea has invited foreign media to witness the dismantling of its main nuclear test site later this month.
Mr Bolton recently said North Korea could follow a “Libya model” of verifiable denuclearisation, but this alarms Pyongyang, which watched Libya’s Colonel Gaddafi give up his nuclear programme only for him to be killed by Western-backed rebels a few years later.
The BBC’s Laura Bicker in Seoul says North Korea – which had long said its nuclear arsenal is essential for its survival as a state – is now making its demands clear.
Mr Kim’s statement, carried by state media, said that if the US “corners us and unilaterally demands we give up nuclear weapons we will no longer have an interest in talks” and “will have to reconsider” attending the 12 June summit in Singapore.
He said North Korea did have “high hopes” but that it was “very unfortunate that the US is provoking us ahead of the summit by spitting out ludicrous statements”.
Kim Kye-gwan is known to be highly respected in the North Korean leadership and has taken part in negotiations with the US before. There is very little chance his comments were not personally endorsed by Kim Jong-un.
Hours before the announcement, in a sign of growing problems, North Korea had also pulled out of a meeting scheduled with South Korea on Wednesday. because of anger over the start of US-South Korea joint military drills.
North Korea had earlier said it would allow them to go ahead, but then called them “a provocative military ruckus” which was undermining its diplomatic efforts.
The sudden change in tone from Pyongyang is said to have taken US officials by surprise. Analysts said North Korea could be trying to strengthen its hand before talks.
The US state department said it was continuing to plan the Trump-Kim meeting, and Mr Trump is yet to comment.