North Korea has conducted a ground test of a new type of high-thrust rocket engine that leader Kim Jong-un is calling a revolutionary breakthrough for the country's space programme.
Kim attended the test at the Sohae launch site, according to a report on Sunday by the Korean Central News Agency, which said the test was intended to confirm the "new type" engine's thrust power and gauge the reliability of its control system and structural safety.
The KCNA report said Kim called the test "a great event of historic significance" for the country's indigenous rocket industry.
He also said the "whole world will soon witness what eventful significance the great victory won today carries" and claimed the test marks what will be known as the "March 18 revolution" in the development of the country's rocket industry.
The report indicated the engine is to be used for North Korea's space and satellite-launching programme.
North Korea is banned by the UN from conducting long-range missile tests, but it claims its satellite programme is for peaceful use, a claim many in the US and elsewhere believe is questionable.
North Korean officials have said that under a five-year plan they intend to launch more Earth observation satellites and what would be the country's first geostationary communications satellite - which would be a major technological advance.
Getting that kind of satellite into place would likely require a more powerful engine than its previous ones. The North also claims it is trying to build a viable space programme that would include a moon launch within the next 10 years.
Tillerson in China
The test was conducted as Rex Tillerson, US secretary of state, was in China on a tour of Asia that has been closely focused on concerns over how to deal with North Korea's nuclear and missile programmes.
It is hard to know whether this test was deliberately timed to coincide with Tillerson's visit, but North Korea has been highly critical of ongoing US-South Korea wargames just south of the Demilitarised Zone and often conducts some sort of high-profile operation of its own in protest.
Earlier this month, it fired off four ballistic missiles into the Sea of Japan, reportedly reaching within 200km of Japan's shoreline.
Japan, which was Tillerson's first stop before traveling to South Korea and China, hosts tens of thousands of US troops.
While building ever better long-range missiles and smaller nuclear warheads to pair with them, North Korea has marked a number of successes in its space programme.
It launched its latest satellite - the Kwangmyongsong 4, or Brilliant Star 4 - into orbit on February 7 last year, just one month after conducting what it claims was its first hydrogen-bomb test.
It put its first satellite in orbit in 2012, a feat few other countries have achieved. Rival South Korea, for example, has yet to do so.