Few issues within international law generate as much attention and controversy as those pertaining to matters with a conflict or security dimension. International law faces various modern challenges within the conflict and security as a result of the emergence of new significant actors and new technologies, as well as growing recognition of the complex relationship between multiple sources of global instability. In the post-Cold War especially, it has become widely accepted that the notion of security must be understood in terms which extend beyond its traditional physical, military and territorial context to embrace appreciation of its ecological, environmental, social, cultural and human aspects. These points are all observed by the author in the introduction to this new text which sets out to provide an up to date appraisal of the core content of, and debates within, international law with regard to such matters.

The title of the book is perhaps a little misleading in the sense that there is no generally recognised branch of international law concerned with all manner of conflict and security related matters. This is implicitly acknowledged by the author herself in nothing that “International Conflict and Security Law” represents a broad sweep of legal frameworks applicable to conflict prevention, the outbreak of war, and the conduct of hostilities. As such, within the confines of under three hundred substantive pages this book purports to cast its eye over a myriad of legal frameworks which would conventionally each be the subject of its own detailed text. This is an ambitious undertaken, but arguably one for which the author is suitably qualified, Laurie R Blank being a widely published professor whose roles have included serving as a US government legal advisor.

The book’s twelve chapters are structured into four parts, each of which represents an area of law which in turn is loosely concerned with a stage in the conflict process. These follow on in a broadly chronological fashion from each other. Part I is titled ‘Conflict Prevention and Collective Security.’ This is arguably the most loosely arranged part of the book, not being concerned with a distinct branch of international law so much as an assortment of themes and issues essentially concerned with mechanisms for preventing or minimising the risk of conflict arising or international security being compromised in the first place. The first of the three chapters contained within this part is concerned with the practice of collective security, seeking to define the concept and its objectives, before setting out the key features of the collective security system created by the UN Charter. The broad approach to security threats in the practice of the UN is emphasised, while reference is also made to the emergence of regional collective security frameworks. Chapter two addresses legal techniques that have been employed to further the goals of disarmament and non-proliferation of arms. The effects of some of the most relevant treaty framework are explored, as is the role of the UN via its principal organs’ adoption of resolutions to tackle threats posed by the existence of weapons of mass destruction in the hands of rogue states. Counterterrorism is the focus of the third chapter, an increasingly important form of activity on account of the growth in number and significance of threats emanating from non-state actors. While it is noted that there is no universally acknowledged definition of terrorism, it is nonetheless demonstrated that a significant number of treaties have been adopted to tackle it while the UN Security Council has also adopted regimes imposing obligations upon states to take measures in this area. The relationship between counterterrorism measures and the protection of human rights is touched upon.

The middle two parts of the book are concerned respectively with the Jus Ad Bellum and Jus In Bello branches of International Law pertaining to armed conflict. Chapter four introduces the Jus Ad Bellum, tracing its development from the Just War tradition through early measures adopted to regulate the use of force by states which culminated in the adoption of Article 2 (4) of the UN Charter which places an outright prohibition on the use of force. The exceptions to this prohibition are briefly stated, before two of these are explored further in the subsequent chapters. The right of self-defence is tackled first. The biggest controversies here arguably concern the question of whether action taken in self-defence may precede an armed attack taking place and the attribution of acts of non-state actors to a state. These form the focus of much of the fifth chapter which also articulates the criteria against which a lawful instance of self-defence will be evaluated. Chapter six considers state practice in respect of any right of humanitarian intervention, illustrating a shift over times in attitudes which have become more favourable to the doctrine, while stopping short of pronouncing its illegality. The emergence of the Responsibility to protect doctrine is noted, before the dangers of the distortion of humanitarian intervention are demonstrated by reference to Russian claims in support of its invasion of Ukraine.

The third part of the book is particularly substantive, attempting to condense as it does a meaningful overview of the huge body of International Humanitarian Law into its four chapters. This commences with an overview of the historical development of the law in this area and its core purposes and principles, in chapter seven, before proceeding in the following chapter to consider the importance of the classification of conflict. Whether a given situation is identified as being international or non-international in nature is central to the question of which substantive treaty-based rules will apply to its conduct. Some of the problems arising from the process of classifying a conflict are probed, it being also noted that additional questions are now posed by the phenomena of the increased significance of cyberspace and outer space as domains within which conflict may arise. Chapter nine considers the various forms of legal protection afforded to different categories of person, ranging from combatants to civilians, during a time of armed conflict, while chapter ten seeks to appraise the various legal rules and principles which place restrictions upon the manner in which conflict is waged via the clarification of what constitute legitimate targets and conditions for the detention of individuals.

The book’s final part is relatively brief and ties together some of the legal issues which arise in the aftermath of conflict. The increased scope and application of International Criminal Law as a mechanism for holding to account the perpetrators of atrocities during warfare is one of the principal stories of international law’s development in modern times, a journey which is detailed in chapter eleven and takes in events from Nuremberg through to the creation of the International Criminal Tribunals and International Criminal Court. The principal international crimes are explored, before some contemporary challenges within International Criminal Law are identified. While criminal accountability is essentially concerned with the punishment of wrongdoers, transitional justice has gained growing interest as a means which can provide post-conflict societies to obtain some “closure” upon the brutality of conflict. Its key principles and some of its more significant mechanisms are appraised in the final chapter of the book.

International Conflict and Security Law is an eminently readable text. This is enhanced by its inclusion of a feature whereby key contemporary controversies or debates are highlighted by their incorporation within boxes, drawing out the real-life relevance of many of the issues explored within the book. The book is admittedly brief in its treatment of the issues which it addresses. This is of necessity given the vast body of law it attempts to touch upon. As a result it serves as a very useful introduction to the relevant legal frameworks and debates for those, principally students, new to the subject before moving on to more comprehensive focused works which tackle more specifically the applicable legal regimes individually.