North Korea has said it may reconsider attending a summit with US President Donald Trump if the US unilaterally insists it gives up nuclear weapons.
The highly anticipated meeting between Trump and North Korea's Kim Jong-un is due to take place on 12 June.
It came about after North Korea said it was committed to denuclearising the Korean peninsula.
Delicate preparations are taking place for the Trump-Kim meeting, but this appears to throw it into doubt.
State news agency KCNA quoted Vice-Foreign Minister Kim Kye-gwan as saying 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 whether we will accept the upcoming DPRK-US summit".
Democratic People's Republic of Korea is the official name for North Korea.
Mr Kim said North Korea "had high hopes that the summit would lead to the easing of the situation on the Korean Peninsula and count as a big step to build a great future.
"However, it is very unfortunate that the US is provoking us ahead of the summit by spitting out ludicrous statements."
Earlier on Wednesday, in a sign of growing difficulties, North Korea pulled out of talks scheduled for the day with South Korea.
Officials were due to meet in the demilitarised zone between the two countries to discuss further details of the agreements they had made at the historic summit last month.
But the North withdrew, angered by the start of large South Korea-US military drills.
The drills - called Max Thunder - had been due to take place around the time of the Winter Olympics in South Korea, but were postponed because of an unexpected thaw in North-South relations.
North Korea had previously said it understood that the drills needed to go ahead.
But KCNA said they were a "provocation" and a rehearsal for an invasion - a return to the sort of language is has used during far more tense times.