'Giuseppe Spatafora's meticulous study provides the best discussion to date on how escalation crosses the direct-indirect thresholds of war. Theoretically ambitious and empirically rigorous, Spatafora breaks new intellectual ground with a welcome contribution to conflict studies that will serve as a point of reference to scholars and practitioners for years to come.'Vladimir Rauta, Head of Department and Director of the Centre for Global Security and Governance, University of Reading, UK'Why do outside states that provide indirect support to civil war parties sometimes escalate by directly joining the conflict? Spatafora's book tackles this important but hitherto underexplored question by drawing on the literature on proxy wars and military interventions, as well as on careful case studies. This is a must-read for anyone interested in understanding an increasingly prevalent aspect of contemporary armed conflict.'Costantino Pischedda, Associate Professor of International Relations, University of Miami, USA