North Korea’s leader Kim Jong Un announced on April 20 to the Korean Workers’ Party that North Korea no longer needs to conduct nuclear tests and stated his intent to close the nuclear test site at Punggye-ri. This announcement presents a significant opportunity for the United States to constrain the future of North Korea’s nuclear weapons program and to build momentum to achieve the elimination of nuclear weapons from the Korean Peninsula. The chance to end the North’s test program should be seized and, if successful, could form the basis for expanding direct contact and trust between Washington and Pyongyang, while expanding the global norm against nuclear testing.

North Korea has conducted six explosive underground nuclear tests since 2006, the last in September 2017. These events have advanced the country’s nuclear weapons capabilities while destabilizing regional and global security. The United Nations Security Council has condemned such tests in multiple UNSC resolutions and called on North Korea to stop all future tests. Thus, it was significant for Kim Jong Un to announce a formal policy change that North Korea would close its nuclear test site at Punggye-ri, stating “nuclear tests were no longer needed.” Of course, this announcement is tied to the strong charm offensive Kim has undertaken since the beginning of the year, and may or may not lead to a true breakthrough on the peninsula. Still, such an opening cannot be overlooked or easily cast aside.

Jon Wolfsthal
Jon Wolfsthal was a nonresident scholar with the Nuclear Policy Program.
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Kim Jong Un’s announcement that he intended to close the Punggye-ri site also included an offer to have US experts and journalists witness the site’s closure. While welcome, a more appropriate process would be for North Korea or for the UN Security Council to invite the Comprehensive Test Ban Treaty Organization (CTBTO), the group tasked with preparing for the entry into force of the 1996 Comprehensive Test Ban Treaty (CTBT), to oversee this process. Moreover, every effort should be made to ensure that this is not purely focused on the Punggye-ri site, but expanded to provide the basis for banning all future nuclear tests anywhere in North Korea. To achieve this, the United States should encourage North Korea to sign the Comprehensive Test Ban Treaty (CTBT)—just as the US and China have done—as part of an initial diplomatic effort to precisely define the current missile and nuclear test freeze and to make it more durable through transparent and legally binding means.

In addition to signing the CTBT, a step that even without full ratification would bind North Korea under international law not to take any steps that would undermine the purpose of the Treaty—namely no more nuclear tests—the United States and its partners should invite North Korea to host CTBTO inspectors to install monitoring equipment in North Korea and to ensure that live signals from the sensors are transmitted to the CTBTO. The CTBTO operates the International Monitoring System (IMS), a global network of seismic, acoustic and other sensors that listen for nuclear explosions. There are over 300 sensors operating or being installed in over 100 countries, including many in China, the United States, Russia, France and the United Kingdom. Installing and operating such sites in North Korea are not required, but could be an important confidence building step. Pyongyang, with US support and encouragement, could invite Comprehensive Test Ban Organization experts to visit the Punggye-ri nuclear test site, verify its status and monitor for any moves to restart operations there. Also, CTBTO personnel could undertake geological experiments that could help refine the understanding of what North Korea has done in the past at the site. Technical assistance from the CTBTO and other states could make this process both quick and beneficial for all of the parties, including North Korea.

Of course, none of these steps would permanently prevent North Korea from resuming nuclear tests in the future. Nothing except a decision by North Korea’s leadership can achieve this goal. This is true for all other states that have adopted nuclear test moratoria or signed the CTBT. Despite this reality, there are a number of significant benefits for the region and for the security of the United States and its allies in creating additional legal and political barriers to the resumption of nuclear tests by North Korea.

Most important, North Korea has historically used nuclear tests both to create instability and leverage over South Korea, China and the United States, and to advance their knowledge of nuclear weapons design and miniaturization. It is possible that Pyongyang has already advanced its program to the point where it can reliably produce and deliver a small nuclear weapon to the United States on a ballistic missile. It is certain, however, that further tests would help advance that knowledge even further, and possibly enable the North to push the design and reliability to the point where it could deliver multiple warheads on a single missile. These developments would further undermine American security and crisis stability, and it is very much in Washington’s interests to freeze North Korea’s nuclear capabilities in place as it seeks to eliminate them under effective verification.

Thus the United States, South Korea and the world have an incentive to prevent or discourage North Korea from ever testing nuclear weapons again. While such steps will not by themselves end or even cap the North’s nuclear program, it will create a barrier to advancing that program or to using tests to stoke tensions.

While not yet in force, the CTBT and its organization are the right way to lock in a test ban in North Korea. All but a handful of countries (including North Korea) have yet to sign the treaty, and the test ban is the legal instrument in place underpinning the global norm against nuclear testing. Signing the CTBT would put the North in an interesting position, on par legally with the United States and China, who have both tested nuclear weapons, and signed but not ratified the CTBT. Signature of the pact, however, puts certain legal obligations on a state, including a legal obligation not to take any action that would undermine the purpose of the treaty—in this case prohibiting all nuclear tests.

One problem for this approach is US policy, which is openly hostile to the CTBT. The 2018 Nuclear Posture Review produced by the Department of Defense goes out of its way to state that it does not support the CTBT even while supporting the International Monitoring System put in place under its terms. This is both unnecessary and unwise, and should be reversed. Obtaining a commitment by North Korea to sign the CTBT is not the holy grail of denuclearization by any means, as Pyongyang has a long history of ignoring and violating international agreements. But the rest of the world also has a long history of using those violations to impose crushing sanctions on North Korea—something President Trump himself claims is responsible for North Korea’s willingness to sit down and negotiate over its nuclear efforts. Thus, even if signed and violated, getting North Korea into the CTBT could have benefits including providing a new legal basis for countering North Korea should it sign the CTBT and then reverse course by resuming nuclear tests. Interestingly, signing the CTBT and supporting its full entry into force would put North Korea in a more moderate position on this one issue than the United States.

It has been suggested that Kim’s offer to close the test site is not as significant as it might appear, arguing that there are some indications that North Korea’s past nuclear tests have made the entire site unstable and unsuitable for nuclear tests. However, Kim himself has noted this skepticism. President Moon’s press secretary Yoon Young-chan quoted Kim Jong Un saying that two test tunnels at the site remain in very good and usable condition. Other evidence, including reports from 38 North, support this statement.

But such concerns miss the larger opportunity. Regardless of Kim’s intention or framing of this issue, he should be encouraged to put in place barriers to the resumption of any nuclear tests anywhere in the country. Using Kim’s April offer as a starting point, there is an opportunity to make progress in building trust, transparency and barriers to North Korea resuming its nuclear activities. Even if not fulfilled, the United States and others should pursue any opening to visit sensitive sites the North, both to encourage greater transparency and access, but also to gain deeper knowledge about their past and possibly ongoing activities.

This article was originally published in 38 North.