Japan and South Korea have chosen dissimilar policy options in the relocation of the US bases for the past few decades. After agreeing with the United States to relocate the US Marine base in Okinawa in 1996, the Japanese government procrastinated in fulfilling the commitment. As the relocation of Futenma remains unresolved and cooperation between Japan and the United States drags on, many policy elites in both countries start to question the robustness of the US-Japan alliance. In the case of South Korea, the memorandum of understanding to move US base in Seoul to Pyongtaek was signed as early as 1990. Although the procedure has been stalled a few times, the US Forces in Korea (USFK) is gradually moving to Pyongtaek. Both Tokyo and Seoul confronted strong public protests and onerous financial burden in changing the US bases. In the mean time, they encountered growing pressure from the United States that tried to make this transformation in line with the US global military strategy. However, Japan has difficulty in honoring its commitment in relocating the US base while South Korea is slowly fulfilling it. What makes Japan more reluctant to cooperate with the United States than South Korea despite the fact that both governments face similar domestic and international pressures? How do Japan and South Korea tackle a dilemma of increasing alliance requirements and the resistance of domestic politics to fulfill these requirements? To put it in a general question, how do states manage systemic pressure and domestic politics in developing and implementing alliance strategies? This research project seeks to explain how international pressure is filtered through domestic factors and under what conditions domestic politics impede alliance cooperation. It offers comparative analyses on Japan and South Korea by examining how policy elites in the two countries handle domestic impediments in relocating US bases. My project is relevant to policy. First, most existing work fails to provide systemic analyses of the US-Japanese and the US-South Korean alliances. They offer a similar explanation that the difference between Japan and South Korea reflects the origins of alliance formation. Few works provide comparative analyses on security policies of Japan and South Korea in the Post Cold War era. This research will offer a novel theoretical framework to explore and compare the cases of Japan and South Korea. Second, my research will be informational particularly for the US policy community. It reveals that effective cooperation between alliance partners is not likely to occur even if states agree with their alliance partners in handling external threats. Alliance cooperation can be bogged down because of internal constraints within Japan and South Korea. Therefore, it is important for the United States to understand allies' internal processes as much as to adjust and redefine common threat perception. It also requires the United States to show patience even if its allies do not follow through with their commitment right away.