SEOUL, Dec. 23 (Yonhap) -- After examining a piece of the debris from a long-range rocket launched by North Korea, South Korean experts have concluded that the communist country in fact had tested its inter-continental ballistic missile technology, the defense ministry said Sunday.
North Korea fired off a three-stage "Unha 3" rocket on Dec. 12, claiming that it was to put a satellite into orbit. The first stage of the rocket fell in the Yellow Sea off South Korea's west coast and the second stage in waters near the Philippines.
Two days after the lift-off, South Korea's Navy retrieved a large cylindrical container 7.6 meters long and 2.4 meters in diameter which is believed to be the upper part of the first-stage rocket that also included a fuel tank and a combustion chamber.
After examining the 3.2-ton wreckage with the sign "Unha" written in Korean on it, a team of 42 South Korean military, rocket and missile experts has concluded that the wreckage is an oxidizer container, which stored red fuming nitric acid, to fuel the rocket's first-stage propellant.
The storable oxidizer that contains highly toxic chemicals is rarely used by countries with advanced space technology, the defense ministry said, quoting the team's findings.
"Red fuming nitric acid was used in missiles developed by the Soviet Union," a team member said, asking that he remain anonymous. "Because it used red fuming nitric acid as an oxidizer, which can be stored for a long time at normal temperature, the team concluded that (the rocket) was intended for testing (the North's) ICBM technology, rather than developing a space launch vehicle."
The South Korean findings reinforced suspicions voiced by U.S. and other Western military experts that the North's rocket launch was in fact intended to test its inter-continental ballistic missile technology in violation of U.N. resolutions.
Following the launch, North Korea claimed that its satellite, called Kwangmyongsong-3, was functioning properly in orbit but Seoul officials believe Pyongyang has lost contact with it, apparently because it is in unstable condition.
The wreckage retrieved has four holes on the bottom, which are believed to be used to supply the oxidizer to the fuel tank, the South Korean investigation team said in a report.
Usually, the oxidizer is carried in a different tank and released in the proper proportion with the fuel when the rocket is fired, according to the report.
The analysis also revealed that the North had used Skud and Nodong missile technology to develop the rocket, which successfully separated at each stage.
"It used four Nodong missile engines for the first stage booster, while utilizing one Skud missile engine to make the second stage propellant in a bid to save time and cost," the expert said.
A simulation of the rocket, assuming the container stores about 48 tons of oxidizer, showed that the propellant is capable of carrying 500 kilograms of warhead and flying over 10,000 kilometers, a distance long enough to hit the western U.S., he said.
The rocket itself was made of a mixture of aluminum and magnesium, AIMg6, and was equipped with a camera tasked with monitoring engines, a propellant motor and fuel pipelines on its side, according to the report.
"While the North is believed to have produced the alloy, there is also possibility that it has imported it from overseas," it said.
Poor welding and uneven surface shows that North Korea seems to have no advanced technology in that area, the report said.
Some components, including a compression censor and electric wires, were identified as imported, the report said, but there were no materials that have violated the Missile Technology Control Regime (MTCR), a voluntary guideline shared by 34 members aimed at limiting exports of delivery systems and related technology for ballistic missiles, it said.
It was immediately unknown whether the rocket is able to make a re-entry to the Earth to hit a distant target, a key element of ICBM technology, because information on the second and third stages was not available, the report said.
The defense ministry earlier said it will not hand over the debris to Pyongyang because the North is an enemy state and the rocket launch violated U.N. resolutions.