This paper attempts to take Myanmar and Cambodia as examples to explore the consequences of constructive interaction between the international community and Southeast Asian countries after the cold war. After the end of the Cold War, Southeast Asia encountered two regional conflicts and crises of global concern. We finds that for Myanmar and Cambodia, the ability of political elites is the key to leading regional and global peace. The ability of political elites not only determines the process of external norms, but also affects the changes of regional norms. As far as Cambodia is concerned, through cooperation with the United Nations and ASEAN, it has rapidly rebuilt its political authority and effectively internalized the international community's peacebuilding norms. Therefore, Cambodia can improve its national capacity and stability after the emergence of political authority. As far as Myanmar is concerned, after the end of the cold war, the political authority still exists in Myanmar, thus maintaining a certain degree of national stability. With the outbreak of the Rohingya crisis in Myanmar in 2015, Myanmar's original national construction gradually began to collapse. On the one hand, Myanmar cannot internalize the international community's peacebuilding norms. On the other hand, due to the decline of political authority, various internal forces began to struggle with each other, which ultimately led to the failure of the country. For the dissemination of international norms, whether in Cambodia or Myanmar, the localization of external norms requires the cooperation of the political authorities to effectively prevent conflicts.