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North Korean leader Kim Jong-un looks during field guidance at an object that appears to be a ballistic missile warhead

Since UN sanctions against North Korea kicked in, North Korean leader Kim Jong-un has taken steps almost daily to demonstrate the North‘s nuclear ability.

North Korean media reported the test launch of a large-caliber rocket launcher on Mar. 4, the development of a ballistic rocket and a miniaturized and standardized nuclear warhead on Mar. 9, the test launch of a ballistic rocket on Mar. 11 and the acquisition of technology for nuclear warheads reentering the atmosphere on Mar. 15.

With each report, Pyongyang appears to be responding to doubts in the international community about the nuclear technology that the North claims to possess. This is also the sequence followed by the US, the Soviet Union and China when they were developing nuclear weapons.

Technically speaking, if the North has successfully “detonated nuclear warheads and test launched several kinds of ballistic rockets that can equip nuclear warheads,” as Kim Jong-un claims, then it is effectively putting the finishing touches to its nuclear arsenal. This makes it difficult to believe that the “stern retribution” by the international community and the South Korean government is accomplishing much.

The key to deploying an ICBM (intercontinental ballistic missile) equipped with a nuclear warhead is reentry technology - the technology by which a missile that has left the earth’s atmosphere enters it again.

The practice test for which Kim provided “field guidance” on Tuesday was intended to assess whether a warhead containing a nuclear weapon and a detonator could endure the heat of reentering the atmosphere.

“Years of intense research have succeeded in developing heat-resistant material that can be used to produce the rocket and in enabling this material‘s domestic production,” claimed a report by the North’s Rodong Sinmun newspaper.

A photo that ran in the newspaper shows several layers of a substance covering an object that appears to be a warhead. The substance is presumably made of heat-resistant fiber.

But the South Korean and US governments - along with the majority of experts - consider it unlikely that North Korea has acquired all of the technology required for ICBM reentry.

“I’m inclined to think that they’ve acquired technology for protecting the reentry vehicle with a heat shield,” said Lee Chun-geun, an analyst at the Science and Technology Policy Institute. “But there are no grounds for concluding that they‘ve acquired everything needed for an ICBM to reenter the atmosphere, which would include technology for protecting the detonator from shocks and vibrations and for detailed guidance and control.”

“It’s possible that they‘ve developed reentry technology for mid-range missiles like the Musudan missile. I think it’s very likely they haven’t reached the level of ICBM reentry,” said Kim Dong-yeop, a military expert and professor at Kyungnam University.

South Korean Defense Ministry Spokesperson Moon Sang-gyun described Pyongyang’s claims to have acquired ICBM reentry technology as having come only from them.

“Based on a variety of data, our view is that North Korea has not yet acquired the technology for ICBM reentry,” Moon said.

Seoul and experts are also doubtful that Kim’s declaration about detonating a nuclear warhead can be seen as a fifth nuclear test.

“It’s possible to confirm whether the warhead is adequately protecting the detonator and whether the detonator will go off when you want it to without inserting nuclear materials,” said Kim Dong-yeop.

“It’s very likely that they carried out a test in which they detonated a warhead that only contained a detonator without any nuclear materials. China did the same thing,” said Lee Chun-geun.

“I’m informed that a detonation test of a nuclear warhead is a necessary step in the process of developing nuclear ballistic missiles,” said Moon Sang-gyun. “This cannot be conclusively described as an additional nuclear test.”

Some experts think that Pyongyang’s claim about test launches of “several kinds of ballistic rockets that can equip nuclear warheads” suggests a subtle shift in the North’s nuclear strategy.

“North Korea has always specified the US as the target of its nuclear weapons, but in its recent test launch of a ballistic rocket and its test firing of a large-caliber rocket launcher, it mentioned South Korea as the target of such a strike,” Kim said. “By mentioning ‘several kinds of ballistic rockets,’ Kim appears to be referring to test launches of various short-range and long-range missiles, in addition to the ICBMs that are intended to target the continental US.”

By Kim Jin-cheol, staff reporter and Park Byong-su, senior staff writer

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