North Korea says it has carried out another "crucial test" at its long-range rocket launch site.
The announcement comes as North Korea continues to pressure Donald Trump over a deadline set for the end of the year by leader Kim Jong Un to salvage faltering nuclear negotiations.
North Korea's Academy of Defence Science did not specify what was tested on Friday.
Days earlier, the North said it conducted a "very important test" at the site, prompting speculation that it involved a new engine for either a space launch vehicle or an intercontinental ballistic missile.
Negotiations broke down after the US rejected demands by North Korea for a relief on sanctions in exchange for a partial surrender of the North's nuclear capabilities at Kim's second summit with Mr Trump in Vietnam in February.
Talks resumed between the two leaders in June when they agreed to resume talks but a further meeting in October ended in deadlock over what North Korea called America's "old stance and attitude".
US Ambassador Kelly Craft has been critical of the North's ballistic testing activity during a United Nations Security Council meeting saying the tests were "deeply counterproductive" and risked jeopardising prospects for future talks.
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She also cited North Korean hints of "a resumption of serious provocations," which she said would mean they could launch space vehicles using long-range ballistic missile technology or test ICBMs, "which are designed to attack the continental United States with nuclear weapons."