Following a record number of North Korean missile launches, as well as tests by South Korea, assertions have been widely and uncritically made that Seoul is participating in an inter-Korean arms race. This paper challenges that paradigm by arguing that South Korea’s military acquisitions, displays, and testing of new weapons are better explained as proactive efforts to build military capabilities to support national security priorities in a broader context, rather than reactions to the threat from North Korea. While North Korea’s reasons for weapons testing are well-documented, South Korea’s military buildup in recent years has received far less attention. This paper examines drivers behind South Korea’s military investments and makes recommendations for how the Republic of Korea (ROK)-United States alliance could incorporate these capabilities into alliance military operations beyond simply deterring or defeating North Korea. To do so, it examines how broader drivers affect ROK strategic thinking, the demands this puts on the ROK military, and how those demands translate to specific defense acquisitions. With the start of a new ROK presidential administration, it is an opportune time for Seoul and Washington to coordinate approaches on capabilities development in ways that would benefit both countries in the years to come.