U.S. military bases are distributed across over forty countries with approximately eight hundreds installations. Yet, base politics has received rather limited attention from IR scholars to date. South Korea and Turkey have hosted American troops for more than six decades. After the end of the Cold War, the issue of U.S. military presence in both countries became questioned and contentious ever now. With a comparative approach, this thesis aims to examine how host nations’ domestic politics influences in base politics. Focusing on base politics during the post-Cold War era, this thesis demonstrates that while high severity of threats to host nations stabilizes the U.S. military presence in host nations, high anti-American sentiment restricts U.S. military operations from bases in host nations. In particular, this research examines base politics under each leadership of the two countries in an effort to analyze influence of two independent variables – severity of threats and anti-Americanism – on base politics which is a dependent variable. When the national security of South Korea and Turkey is threatened, both countries are likely to count on the protection from a more powerful military ally which is the United States. Nonetheless, high anti-Americanism which was increasingly observed after 2002 in both countries has strained alliance relationships in regard to U.S. military bases.