US President Donald Trump • North Korean Leader Kim Jong-un
North Korea's ambassador to the UN has rejected Washington's call for "sustained and substantial dialogue," saying that the denuclearization sought by the Trump administration is already "gone out (sic) of the negotiating table."

"We do not need to have lengthy talks with the US now and denuclearization is already gone out of the [sic] negotiating table," ambassador Kim Song said in a statement on Saturday. Song added that the Trump administration's calls for dialogue are a "time-saving trick" to push the denuclearization issue past next year's election.

As Song released Pyongyang's latest statement, US President Donald Trump and South Korean President Moon Jae-in held a telephone discussion, brainstorming ways to restart diplomacy with North Korea.

Pyongyang has given the United States a year-end deadline to abandon its demand for unilateral denuclearization, lest leader Kim Jong-un choose a "new approach."

"It is entirely up to the US what Christmas gift it will select," Vice Minister of Foreign Affairs Ri Thae Song said in a statement on Tuesday. Assuming the US does not drop the denuclearization demand, the North Koreans will likely return to issuing sporadic threats against the US. State media hinted at this on Wednesday, warning Washington that all-out war could break out between the two nations "at any moment."

Trump, for his part, has not shied away from threats either. Though the president has not threatened Kim with the "fire and fury" that he did in 2017, he has cautioned his North Korean counterpart that "if we have to, we'll use" the might of the US military against him.

Trump and Kim have met three times since last June. While the summits were historic, and gave both leaders an opportunity to boast about moving to bring peace to the Korean peninsula, no concrete progress towards denuclearization has been made, and Pyongyang has restarted missile testing in recent months.