North Korea says it has conducted another crucial test at a long-range satellite launch site, to bolster its strategic nuclear deterrence.
It comes after the country carried out a test yesterday.
The country's state media outlet KCNA said that North Korea had carried out a "very important" test at the Sohae satellite launch site.
The test was carried out at a rocket testing ground that US officials once said North Korea had promised to close.
The latest KCNA report called the event on Friday a "successful test of great significance" but did not specify what was tested.
It comes as a year-end deadline North Korea h has imposed nears, warning it could take a "new path."
The KCNA report called it a "successful test of great significance" on Saturday but did not specify what was tested.
South Korea's defence ministry said the country and the US are cooperating closely in monitoring activities at major North Korean sites including Tongchang-ri, the area where Sohae is located.
It comes after the hermit state's leader Kim Jong-un was pictured riding a white horse up North Korea's tallest peak, Mt Paektu.
The mountain is celebrated as totemic of Korean revolution and the birthplace of Mr Kim’s father, and the propaganda spectacle marked the second symbolic ride by the leader this year.
Mr Kim is said to visit historic sites on the mountain ahead of major decision-making.
State media reported that his horse-ride up the peninsula's highest peak was aimed at instilling a ‘revolutionary spirit’ in the people, amid the continued tensions between Pyongyang and Washington DC over denuclearisation talks.
Missile experts said it appeared likely the North Koreans had conducted a static test of a rocket engine, rather than a missile launch, which are usually quickly detected by neighbouring South Korea and Japan.
"If it is indeed a static engine test for a new solid or liquid fuel missile, it is yet another loud signal that the door for diplomacy is quickly slamming, if it isn't already," said Vipin Narang, a nuclear affairs expert at the Massachusetts Institute of Technology in the US.
"This could be a very credible signal of what might await the world after the New Year."
Tensions have risen ahead of a year-end deadline set by North Korea, which has called on the US to change its policy of insisting on Pyongyang's unilateral denuclearisation and demanded relief from punishing sanctions.
On Saturday North Korea's ambassador to the United Nations said denuclearisation was now off the negotiating table with the United States and lengthy talks with Washington are not needed.
The test is the latest in a string of statements and actions from North Korea designed to underscore the seriousness of its deadline.
North Korea has announced it would convene a rare gathering of top ruling-party officials later this month.
Such meetings and propaganda displays like Mr Kim's horse-ride often come ahead of major announcements from the state's authorities.
While North Korea has not specified what its "new path" could be, observers have suggested the launch of a space satellite is a possibility.
They say that would allow Pyongyang to demonstrate and test its rocket capabilities without resorting to overt military provocation such as an intercontinental ballistic missile launch.
"Such testing is meant to improve military capabilities and to shore up domestic pride and legitimacy," Leif-Eric Easley, a professor at Ewha University in Seoul, said of Saturday's test.
"North Korea is avoiding violations of its long-range missile test moratorium for now, but it is still improving the propulsion and precision of its missiles so that it can claim a credible nuclear deterrent," he said.
US President Donald Trump told reporters in June 2018 after his first summit with Mr Kim that North Korea had pledged to dismantle one of its missile installations, which U.S. officials later identified as Sohae.
Shortly after that summit, analysts said satellite imagery showed some key facilities at Sohae being dismantled.
However, in the wake of the second summit between Trump and Mr Kim earlier this year, which ended with no agreement, new imagery indicated the North Koreans were rebuilding the site.
At the time Trump said he would be "be very disappointed" if the reports of rebuilding were true.
"Remember this is at the site that was supposedly dismantled as a 'denuclearisation step,'" Mr Narang said.
"So this is a first step at 'renuclearising.'"
In recent weeks, media reports indicated a high number of US military surveillance flights over the Korean peninsula, suggesting North Korean tests were imminent.
