The AUKUS partnership between Australia, the United Kingdom, and the United States is one of the most audacious defense industrial efforts to meet the challenge of China’s rising military power.1 While most attention has focused on what is called ‘Pillar 1’ to construct a fleet of nuclear-powered, conventionally armed submarines, the three AUKUS countries are also pursuing ‘Pillar 2’ cooperation to develop cutting-edge military technologies that complement the submarine enterprise. Three years since it was announced, the potential expansion of Pillar 2 membership to include other U.S. allies and partners marks a new phase in minilateral security cooperation in the Indo-Pacific.2 But should the Republic of Korea join AUKUS Pillar 2?

Introduction
1. Understanding AUKUS Pillars 1 and 2
2. Expanding AUKUS Pillar 2
3. KAUKUS vs. JAUKUS: Unpacking Relations
4. Defense Trade Control Considerations
5. Five Options for ROK Consideration
Conclusion