Despite being a potentially important deadline, North Korea has shared few details on what exactly might happen if it is missed
North Korea has doubled down on leader Kim Jong Un's year-end deadline for the United States to reconsider its approach in denuclearization negotiations after the latest attempt at talks ended in disagreement.
A spokesman for North Korea's foreign ministry said in a statement carried by state media on Sunday Washington had until the end of 2019 to come up with a "new calculation method."
Despite being a potentially important deadline, North Korea has shared few details on what exactly might happen if it is missed. Here is what we know - and don't know - about the looming deadline.
Kim Jong un's deadline
The deadline was first set by Kim in April, when talks were stalled in the wake of a failed summit with US President Donald Trump in Hanoi two months earlier.
Kim said in a speech to the Supreme People's Assembly he would wait until the end of the year for the United States to decide to be more flexible.
In a report on that speech, state news agency KCNA quoted Kim as saying: "It is essential for the US to quit its current calculation method and approach us with a new one."
Trump and Kim have met three times: in Singapore last year, in Hanoi in February, and at the demilitarized zone between North and South Korea in June.
They built personal goodwill at those meetings and in a number of letters but they have failed to agree on a deal to lift sanctions in exchange for North Korea abandoning its nuclear and missile programmes.
What does the deadline mean?
At the time, Kim suggested that the deadlock in talks with the United States had made him question his self-imposed moratorium on testing nuclear weapons and long-range ballistic missiles.
Other North Korean officials have also hinted that a lack of progress in talks with the United States could mean a return to such tests, but Pyongyang has otherwise been vague in describing the deadline.
"We really don't know what the North Koreans will do once their end-of-year deadline passes," said Daniel DePetris, a fellow at Defence Priorities, a Washington-based think tank.
North Korea bristled when US Secretary of State Mike Pompeo played down the deadline.
"The meaning is that the US should get rid of the root cause that pushed us into a nuclear state and obstacles on the way to denuclearisation by its own hands; otherwise no one can predict how the situation on the Korean peninsula will turn out," a North Korean foreign ministry official said in April.
Why the end of the year?
Kim did not explain why he chose the end of 2019 as the deadline.
Analysts say there is no obvious reason beyond Kim's annual New Year's address, when the North Korean leader often makes major announcements and sets goals.
For example, Kim used his New Year's speech at the beginning of 2018 to reverse a year of fiery rhetoric and signal an interest in engaging with South Korea.
Kim then used his 2019 New Year's speech to warn that North Korea might be "compelled to explore a new path" to defend its sovereignty if the United States "seeks to force something upon us unilaterally and remains unchanged in its sanctions and pressure."
That's a theme that North Korean negotiators have maintained in their efforts to press US officials for concessions.
It is a major consideration for North Korean officials tasked with negotiating with the United States even if the exact implications of the deadline are still unclear, said John Delury, a North Korea expert at Yonsei University in Seoul.
"It comes down from on high, so it's shaping the whole process," Delury said. "They still have room for the process to continue into the new year, but it does create some time pressure."