North Korea has conducted a "very important test" at its Sohae satellite launch site, state media reported, as nuclear negotiations between Pyongyang and Washington remain deadlocked.

"The results of the recent important test will have an important effect on changing the strategic position of the DPRK once again in the near future," KCNA reported, using the initials of North Korea's official name, the Democratic People's Republic of Korea.

North Korean leader Kim Jong-un had agreed to shut the Sohae site during a summit last year with South Korean President Moon Jae-in in Pyongyang as part of trust-building measures.

Mr Kim has also held three meetings with US President Donald Trump since June 2018 but little progress has been made in efforts towards denuclearisation.

The latest test comes as Pyongyang increases pressure ahead of its end-of-year deadline for the US to propose a new offer to kickstart stalled nuclear talks.

On Thursday, the North's vice foreign minister warned of returning to a war of words with the US, threatening to resume referring to Mr Trump as a "dotard" - Pyongyang's nickname for the US leader at the height of tensions in 2017.

The comments came a day after it warned that if the US used military force against the North it would take "prompt corresponding actions at any level".

At the recent NATO summit, Mr Trump boasted about Washington's "most powerful military", adding: "Hopefully, we don't have to use it, but if we do, we'll use it. If we have to, we'll do it."

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, and on Wednesday state media showed photos of leader Kim Jong Un taking a second symbolic horse ride on the country's sacred Mt Paektu.

Such meetings and propaganda blitzes often come ahead ofmajor announcements from North Korean 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, allowing Pyongyang to demonstrate and test its rocket capabilities without resorting to overt military provocation such as an intercontinental ballistic missile (ICBM) launch.