The detection failures coincide with a noticeable increase in North Korean ballistic missile testing. Since May 2019, North Korea conducted 12 weapons tests. The most recent missile test involved a submarine-launched ballistic missile that highlighted Pyongyang’s attempt to secure a second-strike capability.

North Korea will likely continue conducting periodic missile tests if the regime insists on keeping its nuclear weapons and ballistic missile programs. After the failed talks in Hanoi, Vietnam, and Stockholm, Sweden, these ongoing North Korean tests reaffirm Kim’s intent to keep all of his weapons while extracting concessions from the U.S. and its allies with vague promises to disarm.

South Korea must ensure that its ballistic missile defense capabilities reach their full potential to deter and defend against the North Korean threat. Seoul, which currently possesses three Sejong the Great-class KDX III destroyers equipped with the Aegis ballistic missile defense system, plans to increase its Aegis fleet by building three more comparably equipped destroyers by 2028.

While increasing the size of the fleet will help bolster Seoul’s defenses, South Korea’s Aegis vessels can only exchange targeting data with U.S. vessels, and not with Japanese ones. This is because U.S. and South Korean vessels share a common encryption system, whereas Japanese vessels have a different one. Information sharing would not only enhance ship-to-ship interoperability between the U.S. and South Korea but also ensure the Aegis ballistic missile defense system has a robust capability to defend against North Korean missiles.

In 2016, Tokyo and Seoul sought to overcome this hurdle with a workaround, signing the bilateral military intelligence sharing agreement known as the General Security of Military Information Agreement, or GSOMIA. Japan’s Ministry of Defense described the GSOMIA “as a framework for protecting various confidential information including information regarding North Korea’s nuclear and missile threat.”

This pact enabled South Korea and Japan to relay information about North Korean missiles that their Aegis vessels could not share with one another. Unfortunately, Seoul announced in August that it would not renew GSOMIA amid the two nations’ ongoing trade dispute. Despite its focus on economics, this dispute reflects South Korea’s deep-seated grievances that stem from imperial Japan’s role as a colonial power on the peninsula.

Fortunately, despite the complex roots of Tokyo and Seoul’s persistent strife, South Korea continues to respect GSOMIA, at least pending its expiration on Nov. 22. Under GSOMIA, South Korea earlier this month shared with Japan its assessment of North Korea’s submarine-launched ballistic missile, helping Japan correct its mistaken evaluation that Pyongyang launched two short-range missiles, rather than a single sub-launched ballistic missile that can strike more extended-range targets.

This case illustrates how intelligence sharing could help Japan and South Korea construct a more comprehensive understanding of the threat from Pyongyang.