提　　要 1958年8月23日共軍對金門發動砲擊，當時美國國務院與國防部為因應臺海危 機，採取一系列之外交與軍事因應方案。本文試圖釐清下列研究問題：首先，國務 院內部在危機前對外島防衛立場之爭議、危機中避免衝突升高之建議，以及危機後 推動裁減外島駐軍之爭辯等，分別為何？其次，國防部內部對於危機前外島防衛與 使用核武之爭議、危機中美軍艦外島護航之情形，以及危機後美軍停止護航之爭辯 等，分別為何？最後，國務院與國防部之間對於動用核武的爭論上，為何國務院能 夠位居上風？至於本文研究主旨則是：由於艾森豪(Dwight David Eisenhower) 總統對於處理臺海危機之思維，主要以「外交為主、軍事為輔」；因此，國防部所 提出風險較高之建議未獲採納，而國務院以外交斡旋之提案則較獲總統青睞。

Abstract On August 23, 1958, the People's Liberation Army fired heavy artillery shells against Quemoy. Soon after which, the US State Department and Department of Defense initiated a series of diplomatic and military measures to lessen the military tension across the Taiwan Strait. This paper aims to answer the following questions. First, within the State Department, what were the disputes in defending the offshore islands before the crisis? What were the proposals being raised in avoiding crisis escalation? What were the arguments in implementing the reduction of the offshore islands' forces after the crisis? Second, within the Department of Defense, what were the disputes in the defense of the offshore islands, in the use of nuclear weapon before the crisis and in escorting Taiwan's vessels to the offshore islands during the crisis? What were the debates in suspending escort mission after the crisis? Finally, what were the arguments between State Department and Department of Defense concerning the use of nuclear weapon? The main theme of this paper is that based on President Eisenhower's mindset of“diplomatic first and military second”in diminishing the crisis, the Department of Defense's high risk proposal of military response were turned down by Eisenhower. Thus, the lower risk proposal of diplomatic measures recommended by State Department gained an upper hand in the decision making process.