從離岸平衡觀點時看美菲同盟關係

晚近美國興起大戰略辯論，其中，美國取得菲國基地激起菲人反對，以及菲國失去黃岩島，是否與歐巴馬採離岸平衡戰略有關，值得探討。本文認為，美國尋求基地與迴避安全責任，皆符合離岸平衡宗旨，但如何介入危機則受民意變化與對手可知性所影響。黃岩島對峙時，美國民意並未期待政府強硬，且中國會如何反應不可知，歐巴馬遂以駐軍宣示應對。仁愛暗沙對峙時，美國民意期待政府強硬，且中國會如何反應較易掌握，歐巴馬乃以暗示安全承諾應對。

關鍵字

歐巴馬；離岸平衡；美菲同盟；黃岩島；仁愛暗沙

並列摘要

Recently, academic debate on American grand strategy has seen a renewed upsurge. In this context, it is worth studying whether the rising anti-base sentiment in the Philippines around the signing of the Enhanced Defense Cooperation Agreement and the Philippines’ loss of control over Scarborough shoal should be attributed to Obama's embracing an offshore balancing strategy. This paper holds that the demand for bases and the avoidance of security guarantees on the part of the United States are in line with the objective of the offshore balancing strategy. However, it is American public opinion and information on the enemy's preference that have more influence on the way the U.S. handles Philippines-China confrontation in the South China Sea. During the China-Philippines standoff on Scarborough Shoal, the demand of the American public for tough action was low and the information on how China would respond insufficient. As a result, Obama adopted the option of increasing military presence. By contrast, facing an increasing public demand for tough action and having more information on China's calculations, Obama allowed an implicit security commitment to solve the standoff on the Second Thomas Shoal.