A Way Forward With North Korea: The Comprehensive Nuclear-Test-Ban Treaty


Given the vitriolic rhetoric between the United States and North Korea over the past year, few could have predicted that Supreme Leader Kim Jong Un would choose this time to implement a near-term moratorium on nuclear testing. Yet, here we are. On April 20, Kim announced precisely such a moratorium, along with closure of the Punggye-ri test site and a freeze on ballistic missile tests. Han Tae-song, the regime’s ambassador to the United Nations in Geneva, took the message a step further at the multilateral Conference on Disarmament, stating that the “DPRK will join international disarmament efforts for a total ban on nuclear tests.”

Experts are justifiably skeptical of the prospects for voluntary North Korean denuclearization. However, the regime’s rhetoric raises an opportunity for Kim and President Donald Trump to negotiate a formal end to the controversial testing program that has produced six underground nuclear explosions. One way to do this would be for North Korea to join the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

The treaty has 183 state signatories — 166 have ratified — and bans “all nuclear explosions on Earth whether for military or for peaceful purposes.” Prior to returning to academia, I led U.S. Department of Energy technical delegations around the world to support the CTBT. Our team collaborated with foreign counterparts and the CTBT Organization (CTBTO) to enhance monitoring of nuclear explosions and other geophysical events, as well as prepare for future on-site inspections.

Based on my experience, North Korean accession to the CTBT deserves a hard, thoughtful look in both Washington and Pyongyang. Termination of nuclear tests on the Korean Peninsula is clearly in line with U.S. national security interests, and joining the treaty is a feasible concession for Kim to offer Trump. And the experts of the CTBTO are uniquely prepared to verify the permanent closure of Punggye-ri. Most importantly, the CTBT offers the best prospects for quickly rolling back elements of the North Korean nuclear weapons program.

With few up-front costs, Kim could signal his goodwill

Contrasting U.S. and North Korean definitions of denuclearization make nuclear disarmament appear unlikely in the next few years. North Korea recoiled at initial suggestions by U.S. officials that the regime should adopt the “Libya model” of complete, verifiable, irreversible dismantlement. Indeed, assessments by the CIA as well as the Pentagon have cast doubts on the possibility of denuclearization. Trump himself has now even tried to walk back expectations for the nuclear diplomacy.

But even if Kim isn’t prepared to give up his arsenal anytime soon, there are good reasons to believe he would be willing to accept the CTBT. Beyond North Korea’s statement in Geneva, Kim’s announcement of the moratorium strongly suggests he would be amenable to the treaty. He declared, “Under the proven condition of complete nuclear weapons, we no longer need any nuclear tests” and “the nuclear test site … has also completed its mission.” That wording sounds bad for immediate denuclearization prospects, but great for the test ban.

Joining the treaty would also be a demonstration of North Korea’s long-term intentions and goodwill. In the short term, the regime would simply be legally foreswearing the tests Kim says they no longer need. Beyond that, however, Kim would be tying his hands by ending the provocative nuclear testing program.

Calling it quits after carrying out six test explosions would do much more than limit Kim’s ability to send the international community into a frenzy with each test. It would close off numerous opportunities for North Korea to qualitatively improve its nuclear weapons by developing more advanced warhead designs, making weapons smaller and lighter (hence more deliverable), or investigating how to deploy multiple-independently targetable reentry vehicles on missiles. Given the regime’s limited amount of testing data and lack of supercomputing simulation capabilities, these advances would be extremely difficult — or in some cases nearly impossible — without foreign technology transfers.

Since Kim seems satisfied and confident in existential deterrence and the regime’s ability to deliver nuclear warheads mounted on ballistic missiles, adopting the CTBT would be both a very feasible and a very significant concession.

Verification matters

Verification measures, not informal pledges or even treaty texts, are the heart of nuclear arms control. For instance, while the New Strategic Arms Reduction Treaty between the United States and Russia was only 17 pages long, its protocol laid out an additional 165 pages of procedures for intrusive inspections, telemetry, and other verification measures.

North Korea did indeed destroy facilities at its test site on May 24 in the presence of a group of international journalists. But the journalists watching the show were not technical experts in on-site inspection. They were not geophysicists who could analyze local seismic data to measure the magnitude of exploding tunnels to make sure they were actually being destroyed — not just temporarily sealed off. Nor were they versed in multi-spectral imaging to detect terrain abnormalities, or magnetic and gravitational field monitoring to locate hidden underground testing infrastructure and cavities. The journalists watching from afar also weren’t prepared to take environmental samples in the tunnels prior to their alleged destruction, which might help the world understand the activities that have taken place at Punggye-ri in the past.

A series of worrisome reports have emerged in the aftermath of North Korea’s publicity stunt. Apparently, the regime rescinded invitations for U.S. and South Korean technical experts to observe the fireworks. Some facilities at the site remain untouched, and personnel may have removed sensitive equipment in the days leading up to the demolition activities. If Kim is serious about the path toward disarmament, verification is sorely needed at the test site. Informal pledges simply will not cut it.

By joining the test ban, North Korea would establish ties with the CTBTO, which is the most qualified organization to verify its test site dismantlement. Many followers of arms control know the organization best for its global International Monitoring System of seismic, infrasound, hydroacoustic, and radionuclide stations that easily detected all six North Korean tests. But the CTBTO also has a dedicated corps of inspectors from around the world with expertise in all aspects of on-site inspection of nuclear tests, from visual observation, to environmental sampling, to drilling. While the treaty doesn’t technically permit on-site inspections until it has entered into force (and entry into force is notoriously complicated), to prove his nonproliferation bona fides, Kim could still invite the CTBTO to inspect the test site.

CTBTO Executive Secretary Lassina Zerbo has taken the lead by offering the organization’s support to verify the closure of Punggye-ri. In recent weeks, I attended the Second CTBT Science Diplomacy Symposium in Vienna and spoke with numerous CTBTO staffers about this proposition. They reminded me that the organization successfully tested its on-site inspection procedures in major field exercises in Kazakhstan in 2008 and Jordan in 2014. The CTBTO also visited the shuttered French test site at Mururoa Atoll and has carried out on-site inspection training at the former U.S. Nevada Test Site and Soviet Semipalatinsk Test Site.

Other transparency and verification deliverables could, of course, be emerging from ongoing U.S.-North Korean diplomacy. Perhaps the United States or the International Atomic Energy Agency might be given access to inspect limited North Korean nuclear facilities. These could include a centrifuge enrichment plant toured by former Los Alamos National Laboratory Director Siegfried Hecker, who was blown away by its sophistication. Unlike the centralized nature of testing, however, North Korea has widely dispersed its other fuel cycle and weapon activities throughout the country — posing stark verification challenges.

Thus, of all the options on the table, CTBTO verification of the test site’s closure should be a top priority. It is well-developed, effectively proven, and the most likely way to comprehensively and impartially verify the elimination of a segment of Kim’s nuclear program in the near-term future. If Kim is hiding something at Punggye-ri, the CTBTO will find it. 

Joining the treaty raises the stakes politically for Kim

Notwithstanding these points, some critics will contend that it is hardly a concession for Kim to join a treaty outlawing something he says he doesn’t need to do. But in addition to limiting North Korea’s nuclear advancement as I outlined above, the treaty would place further constraints on the regime in the form of international pressure.

Historically, some states that have chosen not to comply with nuclear arms control agreements have simply refrained from participating in international nonproliferation treaties. North Korea falls into this camp with respect to the CTBT. But in the case of the Nuclear Non-Proliferation Treaty (NPT), North Korea joined and then withdrew, and the international community’s reaction offers a hint at the pressure that might come to bear if the regime did the same with the CTBT.

The different treatment of North Korea on one hand, and India and Pakistan on the other, for their noncompliance with the NPT is illustrative. Pyongyang withdrew in 2003 before conducting its first test three years later. Even though the regime wasn’t obligated by the treaty, UN Security Council Resolution 1718 nonetheless levied harsh multilateral sanctions against North Korea for that first test. By contrast, India and Pakistan, which had never been parties to the treaty when they tested in 1998, each received only verbal condemnation in UN Security Council Resolution 1172.

Put simply, the international community doesn’t take kindly to states that commit to nuclear treaties and then abrogate their responsibilities. North Korea is already under significant pressure for backing away from the NPT. If Kim signed the test ban and then reversed course on yet another arms control treaty, it would become increasingly difficult for China to shield the regime from the Security Council’s wrath.

It’s mutually agreeable and a win for U.S. national security

The United States and North Korea appear headed toward a stalemate. The Trump administration’s hope to apply the “Libya model” of denuclearization is almost certainly a non-starter in Pyongyang, where Kim counts on nuclear weapons for regime survival. In pursuit of this goal, North Korea has carried out 6 nuclear tests and 117 ballistic missile tests. Looking at Kim’s rhetoric, it is clear that he only announced the current moratoria on both types of tests when he had gained confidence in the technical capabilities of his arsenal. Experts are rightly convinced that there is essentially no chance that the regime will suddenly agree to denuclearize or eliminate missiles that raise the risk of mutual vulnerability with the United States.

As such, the negotiators need to focus on obtainable low-hanging fruit. If North Korean denuclearization is going to occur down the road, it will be a lengthy process that requires mutually agreeable confidence-building measures along the way. And getting North Korea to join the CTBT may be a better start than any other proposal on the table.

Regarding the possible outcomes of diplomacy with North Korea, Trump has stated, “The prize I want is victory for the world.” Besides preventing nuclear tests that threaten to destabilize the peninsula, it is obviously in the interests of U.S. and global security to lock Pyongyang into arms control commitments and prevent qualitative advancements in its nuclear arsenal.

The American public would almost certainly agree. Recent research my colleague Jonathon Baron and I published in the Nonproliferation Review shows that a convincing majority of all U.S. demographic groups (gender, race, income, education, region of the country, political party affiliation, etc.) support Senate ratification of the CTBT. These results, of course, showed support for permanently halting U.S. nuclear tests. It’s safe to assume North Korean nuclear tests are even less popular among Americans. Getting Kim to commit to the CTBT could be a major national security policy win on both sides of the aisle.


Stephen Herzog is a Ph.D. candidate in Political Science at Yale University and Nonresident WSD-Handa Fellow at the Pacific-Forum, Center for Strategic and International Studies. Previously, he directed a global scientific engagement program supporting the CTBT for the U.S. Department of Energy’s National Nuclear Security Administration. He led U.S. technical delegations across the Caucasus, Central Asia, Europe, the Middle East, South Asia, and Southeast Asia.

Image: USGS, Public domain, via Wikimedia Commons