Pyongyang’s ultimate intent became clear in January 2021. At the Workers’ Party Congress, North Korean leader Kim Jong-un declared his first two national security priorities: to ‘make nuclear weapons smaller and lighter for more tactical uses’ and to ‘continuously push ahead with the production of super-sized nuclear warheads’. Kim Jong-un has reinforced North Korea’s clear intent to acquire a nuclear arsenal — obfuscating every effort to dissuade it from acquiring and maturing its nuclear weapons program.
North Korea’s highly enriched uranium (HEU) program epitomises the seriousness of its intentions to acquire a nuclear weapon as it likely supports multiple warheads for the full complement of planned systems and envisioned yields.
While Pyongyang has allowed the international community access to its plutonium program, it has consistently denied the existence of its HEU program. Instead, it has stated its uranium efforts are for civilian uses only. But without full knowledge of Pyongyang’s HEU program, verifying arms control compliance is meaningless. North Korea’s significant HEU efforts, and attempts to hide the program, make clear its lack of commitment to arms control — and denuclearisation.
North Korea has developed its HEU program over at least three decades. In the late 1990s it received gas centrifuge assistance from Pakistan via the Abdul Qadeer Khan network. The design, known as the P2 centrifuge, is likely the base of the current North Korean program. Open source reporting suggests North Korea is researching more advanced centrifuges.
One possible pathway would be to develop carbon fibre centrifuges, like what Iran uses, which would greatly increase output.
North Korea is believed to have established at least two HEU facilities, which could house thousands of centrifuge cascades. The expert community has focused much of its attention on the most well-known facility — Yongbyon — with a probable second site at Kangson. There is also growing consensus that a third site may exist but it is unclear where. A joint report by the RAND Corporation and the Asan Institute for Policy Studies from April 2021 postulated a possible site at either Bungang, near Yongbyon, or Sowi-ri.
Yongbyon is often regarded as North Korea’s primary nuclear weapon facility. North Korea brazenly showed the Yongbyon Fuel Fabrication Plant reactor to Stanford University professors in 2010. While North Korea stated that its uranium enrichment supported a civilian light water reactor, experts believe that Yongbyon is intended to support an HEU program with at least 2000–3000 P2-type centrifuges. From publicly available satellite imagery, it appears Yongbyon’s HEU facility was doubled to 4000 centrifuges in 2013.
Kangson has never been acknowledged as an HEU enrichment site. It has likely been operational since 2003 and could have been the template for Yongbyon. There are differing views on Kangson’s potential role in the HEU program, which underscores North Korea’s lack of transparency.
While difficult to verify with certainty, available evidence suggests a number of significant implications of North Korea’s HEU program. By 2017 North Korea probably possessed 8000 centrifuges and could produce 130–150 kilograms of HEU per year. Today that number may be as high as 175 kilograms per year based on improved technology. That means that North Korea may well possesses 600–950 kilograms of HEU. Roughly 25 kilograms of HEU are needed for a nuclear weapon.
North Korea has also likely developed the warheads for its full range of missile systems. Analysts estimate that North Korea could produce approximately six nuclear weapon warheads per year. If one were to include plutonium-based weapons, the possibility of underestimating the amount of HEU produced per year and the conversion of HEU stockpiles to warheads, the RAND Corporation’s estimate of 12–18 warheads per year becomes more plausible.
North Korea has vigorously pursued, and hidden, its HEU program because it has considerable military applications when paired with Pyongyang’s missile options. The joint RAND–Asan report indicated that ‘North Korea has been assessed for many years … to have the designs to build a 500-kilogram HEU warhead capable of being launched on a missile’.
If North Korea intends to make ‘super-sized’ warheads, Pyongyang would presumably pursue thermonuclear weapons, for which HEU is an essential component, and mate them with intercontinental-range ballistic missiles.
Without transparency over its HEU stockpile, North Korea could abide by its plutonium-related commitments — with the aim of winning concessions from the United States and its allies — only to unleash HEU-based capabilities. Any agreement that does not require the verifiable dismantlement of North Korea’s HEU program will only be partially successful.
North Korea’s persistent denials of an HEU program are a serious impediment to any meaningful progress on arms control or denuclearisation. Given that HEU almost certainly supports North Korea’s nuclear weapons program, and evidence of multiple HEU enrichment sites, a lack of transparency on this issue gives Pyongyang a potential breakout opportunity.
Davis Florick is a PhD candidate in the Department of Political Science, Missouri State University.
The views expressed are the author’s and do not represent official US Government or Missouri State University positions.