By Ju-min Park
SEOUL (Reuters) - North Korea has likely mastered the technology to power the different stages of an intercontinental ballistic missile (ICBM) and may show it off soon, analysts say, but it is likely still a long way from being able to hit the mainland United States.
North Korean state media announced its latest rocket-engine test on Sunday, saying it would help North Korea achieve world-class satellite-launch capability, indicating a new type of rocket engine that could be compatible with an ICBM.
The test showed "meaningful" progress, a spokesman for South Korea's Defence Ministry said on Monday, with the firing of a main engine and four auxiliary engines as part of the development of a new rocket booster.
Pentagon spokesman Captain Jeff Davis declined to give a specific assessment of the test but said it was "consistent with the pattern we've seen by North Korea to continue to develop their ballistic missile programme."
The North Korean announcement came as U.S. Secretary of State Rex Tillerson was in Beijing at the end of his first visit to Asia for talks dominated by concern about North Korea's nuclear and missile programmes.
South Korean Defense Ministry spokesman Lee Jin-woo said the test showed progress in engine function, but added that further analysis was needed to show the exact thrust produced and possible uses for the engine.
North Korea's state media released pictures of the high-thrust engine test overseen by leader Kim Jong Un, and said he had called it "a new birth" of the country's rocket industry.
Experts say space rockets and long-range missiles involve fundamentally identical technologies, but with different configurations for trajectory and velocity for the stages.
MOTOR FOR ICBM?
Kim Dong-yub of Seoul's Institute for Far Eastern Studies said he believed North Korea had carried out "a comprehensive test for the first-stage rocket for an ICBM."
"It appears that North Korea has worked out much of its development of the first-stage rocket booster," he said.
Joshua Pollack, of Washington's Nonproliferation Review, said four steering nozzles had also been seen in older, long-range rockets North Korea used to launch objects into space in 2012 and 2016. But he said the main engine was quite different from anything seen previously and appeared roughly the right diameter to serve as either the first or second stage of an ICBM.
U.S. aerospace expert John Schilling, a contributor to the 38 North North Korea monitoring website, said the motor appeared too big for any ICBM North Korea has been known to be working on, but would be a good fit for the second stage of a new space rocket it is planning - or for a yet-unknown ICBM design.
Kim said North Korea had not yet mastered the re-entry technology needed for an ICBM, so still had work to do before it was able to hit the United States. It might though soon be able to demonstrate that it had perfected an ICBM system's booster rocket stage.
"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. They are not going to show it all at once."
A U.S. administration official declined to give a specific technical assessment of the test but said it showed North Korea was "150 percent" committed to its weapons programmes.
"This is one more indication that they are going to act in a way that is counterproductive," he said.
North Korea has conducted five nuclear tests and a series of missile launches in defiance of U.N. resolutions, and experts and Western officials believe it is working to develop nuclear-tipped missiles that can reach the United States.
North Korean leader Kim Jong Un said this year the country was close to test-launching an ICBM, prompting U.S. President Donald Trump to tweet: "It won't happen!"
Last week, Tillerson issued the Trump administration's starkest warning yet to North Korea, saying a military response would be "on the table" if it took action to threaten South Korean and U.S. forces.
Trump told reporters on Sunday he held meetings on North Korea over the weekend and said Kim was "acting very, very badly."
China said on Monday the situation with North Korea was at a new crossroads with two scenarios - a deterioration to war or a diplomatic solution.
"Any chance for dialogue must be seized, as long as there’s hope," Foreign Minister Wang Yi said in Beijing.
(Additional reporting by James Pearson in Seoul and David Brunnstrom, Matt Spetalnick and Idrees Ali in Washington; Editing by Jack Kim and James Dalgleish)