A senior North Korean official has dismissed remarks by US Vice-President Mike Pence as "stupid".
The statement further casting uncertainty about a planned meeting between the two countries' leaders.
Choe Son-hui said Pyongyang would not "beg" for dialogue and warned of a "nuclear showdown" if diplomacy failed.
In recent days, both sides have said that the 12 June Trump-Kim summit could be delayed or even called off.
Pyongyang has insisted it would not give up nuclear weapons unilaterally.
US President Donald Trump on Tuesday said that it was the North that had to meet the conditions for the talks to go ahead.