North Korean dictator Kim Jong-un called the test "a great event of historical significance" that marked "a new birth" of the country's rocket industry.
The Kim regime has a history of making exaggerated claims and belligerent threats that it can't back up, but the latest boast comes amid heightened tensions in the region.
North Korea may have just taken a step towards developing a functional intercontinental ballistic missile (ICBM).
North Korea's test of a rocket engine Sunday showed "meaningful" signs of progress, according to South Korean officials.
"There are more. persons that are involved in the murder of Kim Jong-Nam, we will use the proper legal channels to get them", police chief Khalid Abu Bakar told reporters.
The report indicated that the engine is to be used for North Korea's space and satellite-launching program. That would put parts of the United States in range.
North Korea has conducted a series of missile launches this month, including four on March 6, KCNA reported.
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While the missiles themselves weren't new, the tactic was, analysts said. Rival South Korea, for example, has yet to do so.
Kim attended Saturday's test at the Sohae launch site, according to the Korean Central News Agency, which said the test was meant to confirm the "new type" of engine's thrust power and gauge the reliability of its control system and structural safety. It was developed without "dependence on the technology of other countries", KCNA said. In Seoul the Defence Ministry reacted to the North's latest move.
Japan, which was Tillerson's first stop before traveling to South Korea and China, hosts tens of thousands of USA troops. They have been "playing" the United States for years. He has already accused China of doing too little to help curb Pyongyang's weapons drive.
North Korea has been shy about its missile development goals.
"Any chance for dialogue must be seized, as long as there's hope", Foreign Minister Wang Yi said in Beijing. After the test last April, North Korea's rhetoric was much more intense.
Although North Korea has never flight-tested an intercontinental ballistic missile, it has recently demonstrated significant progress in its missile programs with new engines that could potentially deliver a nuclear warhead as far away as the United States. The statement said: "The Korean People's Army will reduce the bases of aggression and provocation to ashes with its invincible Hwasong rockets tipped with nuclear warheads and reliably defend the security of the country and its people's happiness in case the USA and the South Korean puppet forces fire even a single bullet at the territory of the DPRK".
"What could be next is they would make a new type of ICBM with this new engine system and launch it, but not the entire stages, but to make only the first stage, fly about 400 km and drop", Kim explained, "They are not going to show it all at once".