In this era of globalisation, a multitude of threats impact the security of populations everywhere. These threats now increasingly transgress the traditional boundaries of states and are often non-military in nature, requiring more comprehensive and multifaceted approaches and policy responses. While every threat is unique in terms of its root causes and remedies, philosophical and conceptual methods exist that offer valuable tools for analysis and potential policy recommendations for states facing such threats. This book presents in a novel way eight such approaches that -- when applied against any transnational threat -- may help to enhance the effectiveness of states in their pursuit of long-term and durable security.