By Christopher J. Watterson
In a press conference of their own North Korea clarified their negotiating position, stating that they only sought the removal of five UN sanctions resolutions adopted in 2016 and 2017, and that the ‘area’ that they were willing to verifiably denuclearize in exchange for this was its Yongbyon facility: “We will permanently and completely dismantle all the nuclear material production facilities in the Yongbyon area, including plutonium and uranium, in the presence of U.S. experts and by the joint work of technicians from both countries.” They also added that they were willing “to make commitments on a permanent halt of nuclear testing and long-range rocket launch tests … in order to lower the concerns of the United States.”
If we assume that both statements are accurate (inconsistencies regarding the levels of sanctions relief notwithstanding) and sincere, we can draw the following conclusions: (1) North Korea is willing to give up its Yongbyon facility; (2) North Korea is willing to forgo additional nuclear and missile tests; and (3) the U.S. fears the existence of other critical nuclear weapons sites outside of Yongbyon. From a technical perspective, all three of these conclusions offer insight into the state of North Korea’s current nuclear weapons capabilities.
First and foremost, North Korea’s willingness to forfeit Yongbyon is significant. Yongbyon has historically been the centre of the North Korean nuclear enterprise. It includes North Korea’s only operational 5 MWe reactor and its near-operational light water reactor, both responsible for producing plutonium; it’s chemical reprocessing facility necessary for turning that plutonium into a form useable in bombs; and its only confirmed uranium enrichment facility responsible for producing highly enriched uranium. To “permanently and completely dismantle all the nuclear material production facilities in the Yongbyon area” would therefore, ostensibly, cut off any further production of fissile material – the essential component of a fission bomb.
Like many others I do not believe that North Korea is sincere about giving up its nuclear weapons, and cynically view North Korean denuclearization overtures as tools to milk concession from Washington. Taking this view, North Korea’s willingness to give up fissile material production at Yongbyon is telling. One could interpret this as evidence of the likely second uranium enrichment facility, ‘Kangson’, located around 100km south of Yongbyon. That is, North Korea’s willingness to give up fissile material production in Yongbyon might reflect an intent to shift operations to Kangson, rather than an intent to cease fissile material production altogether. In such a scenario it would make sense for North Korea to make a big show of closing down Yongbyon in exchange for whatever sanctions relief it could get.
This hypothesis is consistent with U.S. concerns regarding critical nuclear weapons sites outside of Yongbyon. It is also consistent with past North Korean diplomatic practice, in which Pyongyang offers to close decrepit nuclear weapons installations for concessions whilst covertly shifting operations elsewhere. The 1994 Agreed Framework, for example, collapsed when it was discovered that North Korea, while following through on commitments to freeze plutonium production at the 5 MWe reactor, was simultaneously expanding its covert uranium enrichment program.
A second explanation of North Korea’s willingness to shut down Yongbyon is that it is actually willing to cease all fissile material production. While this would limit North Korea’s ability to expand its arsenal of fission weapons, this wouldn’t necessarily be a critical blow to its overall nuclear weapons program. First, it’s unknown how much fissile material North Korea already possesses, with some suggesting that the North could possess enough for as many as 60 warheads. Sixty warheads are probably sufficient for a credible minimum deterrent. Second, the recent identification of probable a lithium-6 production plant at Hamhung (another site remote to Yongbyon) and the relatively large yield of the September 2017 nuclear test suggest that North Korea has now unlocked boosted fission and/or thermonuclear weapons, which will drastically reduce the amount of fissile material required per bomb. Thus, a willingness to forfeit its fissile material production might not reflect a North Korean desire to rein in its nuclear weapons capabilities overall, but rather to move up the nuclear weapons assembly line from producing fissile material to producing warheads and fusion fuel.
North Korea’s willingness to forfeit Yongbyon is also significant in that it calls into question North Korea’s ongoing ability to produce tritium, a critical component of boosted fission weapons and, by extension, thermonuclear devices which typically rely on a boosted fission primer. Given its perishable nature tritium stocks need to be steadily replenished, and for North Korea the production of fresh tritium has likely been through its 5 MWe reactor and/or Soviet-era IRT research reactor, both located at Yongbyon. This means that were North Korea to forfeit Yongbyon its tritium stocks and therefore its arsenal of boosted fission and thermonuclear weapons would dwindle. There are three approaches that North Korea could adopt to acquiring tritium in a Yongbyon-less future. The first is to procure it from the international market, though sanctions have made such an approach unreliable. The second is to restart one of its abandoned reactors outside of Yongbyon such as the 200 MWe reactor in Taecheon, though such a move would be easily detectable by intelligence agencies. The third is to utilise raw lithium-6 as an alternative catalyst for the boosting process. This would obviate the need for tritium production at Yongbyon, with North Korea instead relying on its purported lithium-6 production plant in Hamhung. That being said, lithium-6 is a less efficient catalyst than tritium which would theoretically mean lower yields and less reliable two-stage thermonuclear weapons. On this basis it would perhaps be surprising for North Korea to have opted for an obsolete bomb design, even in exchange for sanctions relief. An optimist would take this as evidence of the efficacy of sanctions forcing Pyongyang to make concessions. A pessimist would take this as evidence of Pyongyang’s intention to not follow through on promises to decommission Yongbyon, at least without a clear alternative path to tritium.
What of North Korea’s apparent willingness to forego further nuclear weapons and long-range missile tests? Though this might just be an empty gesture to draw the U.S. back to the negotiating table, it might also reflect growing North Korean confidence in its nuclear weapons and ballistic missile capabilities. 2017 was a bumper year for North Korea in terms of tests of its nuclear weapons and U.S.-centric intercontinental ballistic missile (ICBM) capabilities. Three successful ICBM tests and a nuclear explosion an order of magnitude larger than previous tests supported the now widely held view that North Korea has the ability to get an armed ICBM to the continental U.S.. The only major question mark remaining for North Korea’s ICBM capabilities is the lack of a proven re-entry vehicle. Whilst this is certainly a big question mark, re-entry vehicles can be tested in controlled conditions independent of full ICBM tests, reducing the value of further such tests.
Applying the above premise that North Korea wants to maintain its nuclear weapons and ballistic missile capabilities, and acknowledging recent North Korean gains in these domains, it seems probable that Pyongyang is now happy enough with its U.S.-centric nuclear weapons and ballistic missile capabilities to move from the testing phase to mass production and deployment (a step already taken with its medium-range missiles). An expanded arsenal of nuclear-armed North Korean ICBMs spells trouble for the U.S.: it will increase the surveillance burden, make launches harder to track, and increase North Korean chances of overcoming U.S. missile defense, all the while subjecting more U.S. cities to a nuclear strike.
Overall it would be unwise to interpret North Korea’s overtures at Hanoi as demonstrating a sincere commitment to denuclearization. Offers to decommission Yongbyon and cease nuclear weapons and missile testing more than likely reflect North Korea’s intent to move up the nuclear assembly line whilst simultaneously trying to milk Washington for sanctions relief. Given such considerations, Trump was right to walk away from Hanoi. By doing so the U.S. maintained maximum leverage over North Korea and a high bar for denuclearization, while not succumbing to North Korea’s practice of trading obsolete capabilities for concessions.