Climate change is increasingly affecting national defense security, military operations, and military infrastructure. While in South Korea it has mainly been discussed as an emerging non-traditional security threat, major advanced countries have already integrated climate adaptation into their military strategies. As climate adaptation has become essential for maintaining military readiness and operational sustainability, there is a growing need for systematic identification and management of climate-related risks in the defense sector. This study reviews international trends and key issues in defense-sector climate adaptation and develops a climate risk inventory applicable to the Korean context to support future defense policy and strategy formulation. The analysis draws on the U.S. Department of Defense Climate Adaptation Plan, climate strategies of the U.S. Army, Navy, and Air Force, the U.K. Ministry of Defence strategy, and NATO security impact assessment reports. Based on these sources, direct and indirect climate-related risks affecting military activities were identified. The IPCC risk framework was applied to define hazards and exposure, and risk items were refined according to redundancy, operational relevance, general applicability, and domestic suitability. The results classify defense-sector climate risks into five categories-military facilities and infrastructure; military operations and readiness; logistics and equipment; personnel and human resources; and international security and geopolitics-resulting in 30 risk items. Each item was validated through case analysis using domestic and international literature and media sources. The proposed climate risk inventory provides a practical foundation for defense-sector climate adaptation policy and strategy development.