North Korea has conducted a “crucial test” at a satellite launch site to boost its nuclear deterrent, state media reports.
A spokesman told KNCA news agency it took place late on Friday at the Sohae Satellite Launching Ground, but did not give specific details.
Talks between the US and North Korea about its nuclear programme remain stalled.
Pyongyang has set an end-of-year deadline for the US to offer the country new concessions and has said it will adopt a “new way” if that does not happen.
South Korea’s defence minister said the test earlier in December was a ground-based test of an engine. North Korea had previously promised to dismantle the Sohae site.
US Special Representative for North Korea Stephen Biegun is visiting to South Korean capital Seoul on Sunday. US President Donald Trump has said he still hoped to reach an agreement.
Mr Trump made pursuing diplomacy with North Korea a centre-piece of his foreign policy agenda in 2018 but has failed to extract significant concessions on denuclearisation despite holding two summits with leader Kim Jong-un and even setting foot in North Korea.
The US tested a medium-range ballistic missile over the Pacific Ocean on Thursday – a weapon that would have been prohibited under the 1987 Intermediate-Range Nuclear Forces Treaty which President Trump left earlier this year.