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Signs of increased activity

President Park Geun-hye said at an Apr. 18 meeting of senior Blue House secretaries that evidence of North Korea preparing for a fifth nuclear test had been detected.

Numerous local and foreign news outlets, experts, and research institutions had mentioned signs of a possible fifth test, but Park’s comments were the first public warning to date.

Claims of an imminent nuclear test initially surfaced after the US-based North Korea site 38 North reported on Apr. 13 that commercial satellite images showed increased vehicle activity at a nuclear testing tunnel and facilities in Punggye, a village in Kilju County, North Hamgyong Province. The possibility of a test was also mentioned in an Apr. 17 Yonhap News report, which cited military intelligence authorities as saying vehicle and staff movements at the Punggye test site had recently increased two to three times from their March levels.

For now, the military has avoided any official confirmation based on specific circumstantial data. In response to repeated questioning from reporters at an Apr. 18 briefing, Ministry of National Defense spokesperson said, “While I cannot give any specifics, North Korea is maintaining a state in which it could conduct a fifth nuclear test at any moment.”

If North Korea does conduct a fifth test, it could detonate a nuclear warhead, in contrast with its previous underground detonations of nuclear material such as plutonium or uranium. Having already conducted four tests, its technical need is to prove the ability to produce miniaturized warheads.

Pyongyang published a photograph of a model warhead on Mar. 9. A few days later, leader Kim Jong-un gave instructions to conduct a warhead detonation and a test launch of a ballistic rocket capable of carrying a warhead “in the near future.”

Experts predict one of two methods could be used for a warhead test. In the first, a warhead like the one unveiled on Mar. 9 would be detonated at the Punggye site to allow confirmation on whether it explodes properly and generates the target explosive force. The second approach would be to remove the nuclear material and leave only the detonator on the warhead, which would then be loaded on top of the actual missile. This method would be used to confirm whether the detonator can withstand the vibrations, heat, and pressure of missile flight and function as intended at the site.

If successful, the warhead test is expected to fan fears of North Korea’s nuclear capabilities, as it means Pyongyang is one step closer to being able to miniaturize warheads for missile use. The South Korean military claims the North has achieved a “considerable level” of nuclear weapon miniaturization technology, but say nothing has been “confirmed” on whether the technology has been fully acquired - suggesting it is unlikely to have done so yet.

By Park Byong-su, senior staff writer

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