網路恐怖主義（Cyberterrorism）為「網際網路」（Internet）與「恐怖主義」（terrorism）相互結合之產物，指恐怖份子為求引發嚴重破壞，並造成平民死傷，透過網際網路入侵國家關鍵基礎設施（critical infrastructures），並以之要脅政府或人民完成其政治性、宗教性或社會性目標。至2012年7月為止，對於網路恐怖主義相關議題之討論雖已持續約30年之久，然而各界對於網路恐怖主義之「定義」及「威脅性」兩項基本問題，仍然眾說紛紜，無法取得一致共識，而全球各地缺乏網路恐怖攻擊之實際案例之情況，亦使爭辯益加激烈。 　　在美國政府方面，經過2001年911事件的重大衝擊，其對於恐怖主義相關議題之敏感程度已大幅提高，並陸續制定多項反恐政策。美國是當前國際反恐行動的領導者，既為軍事與科技大國，同時也是諸多國際恐怖組織策劃攻擊之主要目標，有鑑於此，美國政府致力於防治網路恐怖主義，保護國內關鍵基礎設施不受侵襲，以維持社會安定及國家安全，其因應方式足以成為世界各國制定類似政策之重要參考對象。 　　本論文經由探討網路恐怖主義之基本意涵，比較「網路恐怖主義」、「網路犯罪」及「網路戰爭」三個概念之間的差異，嘗試針對網路恐怖主義形成明確之界定；接著綜整各界針對網路恐怖主義威脅性之爭論，以了解網路恐怖主義之真實威脅程度；最後觀察美國自柯林頓（Clinton）政府至今，有關防治網路恐怖主義政策之一系列發展、美國政府如何評估網路恐怖主義之威脅，以及在當前的政策架構之下，為保護國內關鍵基礎設施，其相對應之具體措施為何，試圖對於其整體政策建立客觀評價。 / Cyberterrorism, the convergence of “Internet” and “terrorism,” refers to the specific terrorist activities that were intended to cause massive destruction and casualties, proceeded by intruding the supervisory control and data acquisition (SCADA) systems of national critical infrastructures via the Internet. Even though the discussion of the related issues of Cyberterrorism has continued for nearly 30 years now, neither the definition nor the evaluation of potential threat concerning Cyberterrorism has been settled. No consensus has been achieved. Furthermore, the lack of actual cases of Cyberterrorism attack around the world makes the debates even more intense. After the significant impact of September 11, 2001, the U.S. government has substantially raised the degree of sensitivity of the issues related to terrorism and developed a number of counter-terrorism policies. As the leader of the Global War on Terror and the greatest Power in the world, the U.S. is also the main target of many terrorist groups. With its military and scientific capabilities, the practices of the U.S. government on preventing Cyberterrorism, protecting its domestic critical infrastructures from intrusion, and maintaining social stability and national security would be excellent examples to other nations for the development of their own policies. To clarify the explicit definition of Cyberterrorism, this research refined the basic meaning of Cyberterrorism and distinguished differences among three related concepts: Cyberterrorism, Cybercrime, and Cyberwar. Moreover, this research sought to induct major arguments brought up by scholars in many intense debates on the extent of Cyberterrorism threat. Last but not least, by observing development of the U.S. related policy frameworks, how the U.S. government evaluates the extent of Cyberterrorism threat, and the corresponding measures for protecting the U.S. domestic critical infrastructures, this research presented an objective assessment on the U.S. overall counter-Cyberterrorism policies.