In this paper, Michael Schmitt explores the legality of the attacks against Al Qaeda and the Taliban under the "jus ad bellum," that component of international law that governs when a State may resort to force as an instrument of national policy. Although States have conducted military counterterrorist operations in the past, the scale and scope of Operation Enduring Freedom may signal a sea change in strategies to defend against terrorism. This paper explores the normative limit on counterterrorist operations. Specifically, under what circumstances can a victim State react forcibly to an act of terrorism? Against whom? When? With what degree of severity? And for how long? The author contends that the attacks against Al Qaeda were legitimate exercises of the rights of individual and collective defense. They were necessary and proportional, and once the Taliban refused to comply with U.S. and United Nations demands to turn over the terrorists located in Afghanistan, it was legally appropriate for coalition forces to enter the country for the purpose of ending the ongoing Al Qaeda terrorist campaign. However, the attacks on the Taliban were less well grounded in traditional understandings of international law. Although the Taliban were clearly in violation of their legal obligation not to allow their territory to be used as a terrorist sanctuary, the author suggests that the degree and nature of the relationship between the Taliban and Al Qaeda may not have been such that the September 11 attacks could be attributed to the Taliban, thereby disallowing strikes against them in self-defense under traditional understandings of international law. Were the attacks, therefore, illegal? Not necessarily. Over the past half-century the international community's understanding of the international law governing the use of force by States has been continuously evolving. The author presents criteria likely to drive future assessments of the legality of counterterrorist operatio7.

This book explores the large and controversial subject of the use of force in international law. It examines not only the use of force by states but also the role of the UN in peacekeeping and enforcement action, and the increasing role of regional organizations in the maintenance of international peace and security. The UN Charter framework is under challenge. Russia's invasion of Georgia and intervention in Ukraine, the USA's military operations in Syria, and Saudi Arabia's campaign to restore the government of Yemen by force all raise questions about the law on intervention. The 'war on terror' that began after the 9/11 terrorist attacks on the USA has not been won. It has spread far beyond Afghanistan: it has led to targeted killings in Pakistan, Somalia, and Yemen, and to intervention against ISIS in Iraq and Syria. Is there an expanding right of self-defence against non-state actors? Is the use of force effective? The development of nuclear weapons by North Korea has reignited discussion about the legality of pre-emptive self-defence. The NATO-led operation in Libya increased hopes for the implementation of 'responsibility to protect', but it also provoked criticism for exceeding the Security Council's authorization of force because its outcome was regime change. UN peacekeeping faces new challenges, especially with regard to the protection of civilians, and UN forces have been given revolutionary mandates in several African states. But the 2015 report Uniting Our Strengths reaffirmed that UN peacekeeping is not suited to counter-terrorism or enforcement operations; the UN should turn to regional organizations such as the African Union as first responders in situations of ongoing armed conflict.

1. Law and Force; 2. The Prohibition of the Use of Force; 3. Invitation and Intervention: Civil Wars and the Use of Force; 4. Self-defence; 5. Collective Self-defence; 6. The Use of Force against Terrorism: a New War for a New Century; 7. The UN and the Use of Force; 8.

Now available as an eBook for the first time, this 2006 book from the Melland Schill series considers the main legal issues concerning the use of force by international organisations and states. It assesses the achievements and failures of the United Nations' collective security system, and discusses the prospects ahead. It also deals with the use of force by states in self-defence and on other legal grounds. The book discusses to what extent the rules on the use of force have evolved since the end of the Cold War in order to meet the needs of the international community. It focuses in particular on the military operations directed against terrorism and weapons of mass destruction. The research is developed from the standpoint of the sources of international law. It rejects a static vision of the rules on the use of force, including those enshrined in the UN Charter. Rather, it highlights the interaction between conventional and customary international law and the exposure of both sources to state practice.

An exploration of the relationship between different branches of international law and their applicability to terrorism.

This book examines the different ways in which the laws governing the use of force and the conduct of warfare have become subject to intense scrutiny and contestation since the initiation of the war on terror. Since the end of the Cold War, the nature of security challenges has changed radically and this change has been recognised by the UN, governments and academics around the world. The 911 attacks and the subsequent launch of the 'war on terror' added a new dimension to this debate on the nature and utility of international law due to the demands from some quarters for a change in the laws governing self-defence and humanitarian intervention. This book analyses the nature of these debates and focuses on key issues that have led to the unprecedented contemporary questioning of both the utility and composition of international law on the use of force as well as the practicability of using force, including handling of ‘prisoners’ and ‘security risks’. It also identifies the sources of division and addresses the capacities of security policy and international law to adapt to the changed international environment. This book will of much interest to students of international law, war and conflict studies, and IR and Security Studies in general.

This is the first book to explore the concept of 'Grotian Moments'. Named for Hugo Grotius, whose masterpiece De jure belli ac pacis helped marshal in the modern system of international law, Grotian Moments are transformative developments that generate the unique conditions for accelerated formation of customary international law. In periods of fundamental change, whether by technological advances, the commission of new forms of crimes against humanity, or the development of new means of warfare or terrorism, customary international law may form much more rapidly and with less state practice than is normally the case to keep up with the pace of developments. The book examines the historic underpinnings of the Grotian Moment concept, provides a theoretical framework for testing its existence and application, and analyzes six case studies of potential Grotian Moments: Nuremberg, the continental shelf, space law, the Yugoslavia Tribunal's Tadic decision, the 1999 NATO intervention in Serbia and the 9/11 terrorist attacks.