Why, despite similar North Korean crises within a decade, have East Asia countries responded differently to the U.S. approach toward North Korea, and with what consequences? This dissertation explores the contested nature of the North Korean threat in East Asia and examines its effects on the formation of national interests and the regional order. With an empirical focus on China, Japan, and South Korea, I argue that a region-wide pursuit of greater regional roles shaped the way in which the East Asian countries respond to the U.S. approach. By employing the concepts of role congruence and conflict, this dissertation identifies different pathways to regional order in East Asia. This project is based on a comparative analysis of the post-Cold War political dynamics surrounding the North Korean challenge. To assess the impact of role conceptions on the regional order, I compare the global, regional, and national contexts of post-Cold War North Korean crises, in particular the 1998 North Korean missile crisis and the second North Korean nuclear crisis. For this research, I conducted extensive fieldwork in China, Japan, and South Korea, gathering government documents, speeches, and other primary sources. I also utilized fifty-seven in-depth interviews with government officials and experts, along with a wide set of secondary literature, newspapers, and opinion pieces in each country. This dissertation demonstrates that regional role conceptions play a crucial role in shaping state behavior and influencing regional order, especially in alliance politics and regionalism. The findings from this research also suggest that the success of future global proliferation campaigns hinges on grasping the complexities of regional dynamics surrounding proliferators. Facilitating role congruence among regional actors can contribute to both the success of global proliferation policy and the enhancement of regional order. It is also important to avoid role conflict on the part of the United States: its traditional role as a regional stabilizer and its new role as a global enforcer of counterproliferation and anti-terror strategies. The way it reconciles the two roles and harmonizes global and regional priorities will shape the future course of the East Asian order.