Everything but the Bomb: South Korea’s Nuclear Hedging Strategy

Amid North Korea’s advancing nuclear and missile capabilities and the declining credibility of U.S. extended deterrence, South Korea has a strong motive to pursue its own nuclear deterrent. With its advanced nuclear energy program, South Korea possesses the means to develop nuclear weapons indigenously. However, its opportunity to do so is constrained by the prohibitive costs of nuclear armament—the potential loss of U.S. security guarantees, economic sanctions, and reputational damage. 

To circumvent these costs, Seoul is engaging in “nuclear hedging,” maintaining the capability to develop nuclear weapons rapidly while stopping short of actual weaponization. A key aspect of this strategy involves seeking the ability to produce fissile materials through enrichment and reprocessing, which are currently prohibited under its bilateral treaty with the United States. South Korea justifies its push for treaty revisions by citing energy security, nuclear waste management, and submarine propulsion. While these arguments hold some merit, acquiring enrichment and reprocessing capabilities would significantly reduce the time required for nuclear breakout—from a few years to mere months—thereby significantly lowering the costs of nuclear armament.

Should South Korea acquire nuclear warheads, it could quickly develop a functional nuclear arsenal, as it already possesses dual-capable delivery systems suitable for both conventional and nuclear payloads. Some argue that South Korea’s advanced conventional forces alone could deter North Korea’s nuclear threats. However, Seoul cannot be certain that its conventional capabilities would inflict sufficient harm on North Korea—nor that Pyongyang would perceive them as a credible deterrent.  Consequently, South Korea is likely to continue maintaining the option to develop nuclear weapons until its security environment deteriorates to the point where the benefits of acquiring them outweigh the costs, which nuclear latency would have already reduced.