By Oh Seok-min
SEOUL, Dec. 16 (Yonhap) -- North Korea appears to have carried out a liquid-fuel engine combustion test for a satellite launch vehicle or an inter-continental ballistic missile (ICBM) when it said it conducted "another crucial test" last week, military sources here said Monday.
On Saturday, the North reported that it carried out the unspecified test at the Sohae Satellite Lunching Ground, or the Dongchang-ri site, the previous day, saying it will bolster its "reliable strategic nuclear deterrent."
The test came six days after it conducted "a very important test" at the site, which South Korea believes to have been a rocket engine test.
"The circumstances surrounding the latest test are pretty much the same as those detected during the first test," a military source said.
Though experts were divided on whether the tests used solid or liquid fuel, the source noted that the military authorities believe that liquid fuel seems to have been employed to upgrade its existing engine with a goal of developing a new multiple-stage rocket.
The North's current ICBMs, including the Hwasong-15, use a first-stage rocket powered by a pair of engines. A long-range missile with a multi-stage rocket can carry larger payloads while securing increased stability, according to experts.
Asked about the authorities' analysis of "another strategic weapon" that the North has claimed it is developing, another source stated that long-range rockets would be used either for satellite launch vehicles or inter-continental ballistic missiles.
Following the report on the second test on Saturday, Pak Jong-chon, chief of the North Korean military's General Staff issued a statement saying that new technologies gained in the recent tests "will be fully applied to the development of another strategic weapon" to overpower the U.S.' nuclear threat.
"North Korea appears to be in the final stage of developing a new rocket, though it is too early to say what it will fire off with the advanced one," the source added.
Seoul and Washington see North Korea's satellite launches as a cover for testing long-range missile technology.
Pointing to the North's specific announcement of the latest test's duration of seven minutes, Chang Young-keun, a missile expert at Korea Aerospace University, noted that Pyongyang seems to have tested a two-stage engine for ICBMs, as its single-stage engine combusts for about 127 seconds.
"By turning on and off the two-stage engine to test its ability to shift directions and speed, the North may have been trying to advance the ICBM technology," he said.
Asked about the government's official assessment of last week's test, ministry spokesperson Choi Hyun-soo told a regular briefing without further elaboration on Monday, "In close coordination with the U.S., we keep close tabs on moves in major sites in North Korea, including the Dongchang-ri site."
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