Comparative examination of host-nation political responses in Japan and South Korea since 1955 to the presence of U.S. military forces. Special analytical concern for the similarities and differences in anti-base movements in the two countries, and for their relationship to career opportunities for dissidents beyond a ·protest sub-culture·. Distinctive institutional structures at the sub-national level that shape the broader national impact of local anti-base protest are also considered. Clearly there are commonalities of broader relevance for policy between the cases, including a strong tendency for anti-base protest to correlate with population density. The broad hypothesis, however, is that Japanese and Korean base politics are headed in very different directions, for important structural reasons that policy cannot easily reverse. The postulated structural bias of Korean base politics, in particular, against the U.S. presence there has major implications for U.S.-Japan relations, and for the stability of the Pacific as a whole.