Southeast Asian countries represent a wide range of approaches to military modernisation due to their great diversity in politics, economies, geography and other factors. Bounded by the Pacific and Indian Oceans and located between China and India is the setting for the geostrategic impacts of military modernisation in Southeast Asian countries.Differing from previous research focused on military acquisition, this book additionally covers retention of assets and carefully examines the ageing issues that affect readiness and capabilities. In doing so, it provides a comprehensive view of military modernisation. This book also compares each country's situation in the region in terms of military strength and security challenges to elaborate on the geostrategic impacts of military modernisation. The ten cases of military modernisation in the post-Cold War context provide rich content for readers to explore the evolution of military modernisation in developing countries after 1991.This book sheds light on security studies of Southeast Asia and is a useful resource for academic researchers, policy-makers and defence practitioners.