South Korean President Moon Jae-in’s New Southern Policy (NSP)—the most recent effort by Seoul to boost relations with Southeast Asian countries and India and diversify its relationships beyond four major powers: China, Japan, Russia, and the United States. Yet, at the same time, less of a focus has been placed on how to advance the security aspect of the NSP despite some of the inroads that have been made, as well as the underlying convergences of concerns and interests between South Korea and the countries of Southeast Asia.

This paper addresses this gap by providing insights into South Korea’s security ties with Southeast Asia, based on a close analysis of South Korean and Southeast Asian accounts as well as conversations with officials and scholars on both sides. It makes three arguments. First, while South Korea’s efforts to advance security ties with Southeast Asian states as well as with the Association of Southeast Asian Nations (ASEAN) as a bloc may have been met with mixed results so far, the inroads made still deserve attention and are rooted in several domestic, regional, and global drivers. Second, though these security ties create opportunities for Seoul’s relations with ASEAN countries, they also pose challenges that should not be ignored. Third and finally, advancing security relations between South Korea and Southeast Asian countries will require actions not just on the part of Seoul or ASEAN nations, but also other actors.