North Korea said it had conducted another test at a satellite launch site on Friday to bolster its strategic nuclear deterrence, North Korean state media outlet KCNA reported on Saturday.
The test was conducted at the Sohae satellite launch site, KCNA said, citing a spokesman for North Korea's Academy of Defence Science, without specifying what sort of testing occurred.
It was the second such test at the facility in a week.
KCNA on Sunday said that North Korea had carried out a "very important" test on Dec. 7 at the Sohae satellite launch site, a rocket-testing facility that US officials once said North Korea had promised to close.
That KCNA report called the Dec. 7 event a "successful test of great significance." South Korea's defence minister Jeong Keong-doo said it was an engine test.
The reported tests come ahead of a year-end deadline North Korea has put forth for the United States to drop its insistence on unilateral denuclearisation.
Pyongyang has warned it could take a "new path" amid the stalled talks with the United States. The top U.S envoy for North Korea is set to arrive in Seoul on Sunday for meetings with South Korean officials.
Analysts said such tests could help North Korea build more reliable intercontinental ballistic missiles (ICBMs).
"The point seems to be to remind the United States that North Korea still has space to qualitatively advance its program," said Ankit Panda, a senior fellow at the US-based Federation of American Scientists.
"We had a good hint that whatever they were doing at Sohae was military in nature when the Academy of Defence Science took charge of the announcement, as opposed to NADA, their space agency," Panda added.
Tension has been rising in recent weeks as Pyongyang has conducted weapons tests and waged a war of words with US President Donald Trump, stoking fears that tensions between the two countries could return.
Stephen Biegun, US special envoy for North Korea, will arrive in South Korea on Sunday, Seoul and Washington said on Friday.