日本與南韓在加入美國彈道飛彈防禦體系決策上差異之比較

Abstract

本研究探討身為美國在東亞區域重要盟友的日本與南韓，在1990年代面對美國要求加入彈道飛彈防禦體系時造成日本、南韓決策差異之因素。面對北韓威脅，美國在1990年代開始根據全球性的防衛系統構想飛彈防禦體系，對此美國在東亞區域最重要的兩個盟友日本和南韓對於美國所領導的彈道飛彈防禦體系採取了不同的政策選項：日本同意並開始加入美國的彈道飛彈防禦體系計畫且與美國共同研發技術；南韓則是持續地拒絕美國所提議的計畫，且自主發展南韓彈道飛彈防禦體系。美日、美韓此兩案例有極其類似之處，日、韓兩國同樣面臨北韓飛彈的外在威脅，且與美國皆為同盟關係且在軍事合作上關係密切、互動頻繁；兩國國內也都存在可能對政策造成影響的反美主義，此兩案例在相同的自變項基礎上，但面對安全環境變化，卻出現了日本、南韓分別採取不同政策的依變項。又，日本、南韓國內即使皆經歷保守、進步派政黨輪替，也未改變原有的政策方向。是以，本文梳理現有經驗性與理論性研究當中，對於日本、南韓面對加入美國彈道飛彈體系政策行為的差異的解釋，並檢視這些解釋可接受程度如何、有無任何值得檢討批判之處，最後並提出「威脅可信度」來解釋造成兩案例差異的關鍵因素。

Since the 1990s, Japan and South Korea have chosen dissimilar policy options with respect to the US-led missile defense(MD) systems in East Asia. Japan agreed to join the US MD program and co-develop technologies with the United States. In contrast to Japan, South Korea refused to participate in the US MD program and pursued indigenous anti-missile shield. The choices of two US allies in East Asia were utterly disparate even though both countries lacked the ability to ward off ballistic missile threats. This study will offer comparative analyses on different paths that Japan and South Korea have chosen for their MD policies and what cause the differences. What explains the two countries’ dissimilar MD strategies? In order to solve the research puzzle, we examine existing works about explanations for the dissimilar policy options chosen between Japan and South Korea and present “preventive threat credibility ” to explain the different paths taken by the two countries.