The book is organized into four main parts. Part 1 provides an analytical framework for the book, identifying the most significant post-Cold War shifts in international security and recent theoretical developments in security studies. Part 2 analyses the root causes for contemporary warfare, the dilemmas and debates over military intervention, and the role played by the UN, NATO and other organizations in maintaining international peace and security. Part 3 assesses the challenges of environmental security, including the threat of resource-based conflict, most notably over oil and water, and the perceived security challenges of international migration. Part 4 discusses the new security challenges posed by international terrorism, the proliferation of weapons of mass destruction, and cyber warfare. It explores the strategies and policies adopted by the United States, particularly in the aftermath of 9/11 and assesses the implications of the rise of China and other emerging powers.