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By Jun Ji-hye
North Korea claimed Wednesday that it has perfected the warhead "re-entry technology" necessary to bring a nuclear-armed missile back into the Earth's atmosphere during its test of an intercontinental ballistic missile (ICBM) the previous day.
But the Ministry of National Defense downplayed this, saying it still remains to be seen whether the regime in Pyongyang has mastered such technology.
The ministry added that it is still too early to conclude the North has succeeded in the development of an operational ICBM capable of striking the continental United States.
The North's state-run Korea Central News Agency (KCNA) said the country successfully conducted the ICBM test, supervised by North Korean leader Kim Jong-un, which checked the capability of carrying a large-size heavy nuclear warhead.
The media said the test finally verified "all technical features of the payload of the rocket during its atmospheric re-entry including the heat-resistant features and structural safety of the warhead shroud made of a newly developed carbon compound material, in particular."
Securing missile re-entry technology has been cited as the toughest challenge for the North in developing an ICBM. If Pyongyang's claim is true, that would mean that the North has almost completed its ICBM.
Re-entry technology refers to the ability to construct a shroud that covers the missile's warhead strong enough to withstand the extreme heat and other challenges involved in re-entering the Earth's atmosphere from space. As the covered warhead re-enters the Earth's atmosphere at Mach 24, it needs to be capable of withstanding temperatures of around 7,000 to 8,000 degrees Celsius.
The KCNA said, "The inner temperature of the warhead tip was maintained at 25 to 45 degrees centigrade despite the harsh atmospheric re-entry conditions of having to face heat reaching thousands of degrees centigrade, extreme overload and vibration, the nuclear warhead detonation control device successfully worked, and the warhead accurately hit the targeted waters without any structural breakdown at the end of its flight."
The media added that the latest test also confirmed the operational accuracy and creditability of a newly designed stage-separation system as well as a high-thrust engine.
But Defense Minister Han Min-koo told a National Assembly session that nothing has been confirmed about the North's re-entry technology.
"It would be hard to say that the North has succeeded in mastering the re-entry technology," he said. "If the North wants to prove that its announcement was definitely true, it will need to show a warhead capable of withstanding temperatures of at least 7,000 degrees Celsius."
Han added that the missile launched Tuesday would have been able to fly about 7,000 to 8,000 kilometers if it had been launched on a standard trajectory.
According to the KCNA, the missile flew 933 kilometers for 39 minutes "before accurately hitting the target" in the East Sea." It also said the missile reached a maximum altitude of 2,802 kilometers.
The media noted that the North fired the missile at a high angle as it did in previous launches to exert "no adverse effect on the security of neighboring countries."
