Military spending reflects a nation's priorities and its geopolitical orientation, but in Indonesia it has been compromised by chronic fiscal deficits. The aim of this research was to analyze the historical trajectories of Indonesia’s fiscal gap in military spending from 20023 to 2023 by situating national development within broader global conflicts, including Russia-Ukraine war. A historical method was employed by applying synchronic and diachronic analysis, drawing on archival data from the state budget, official reports from the Ministry of Finance, publications from the SIPRI, and policy documents. The findings demonstrated that historical patterns of defence expenditure consistently revealed a widening fiscal gap between projected requirements and available fiscal capacity. Global geopolitical tensions intensified military modernisation and imposed additional burdens on national budgets. The study concludes that Indonesia’s defence financing challenges cannot be examined solely through contemporary fiscal debates but must be interpreted within a long-term historical narrative of deficit budgeting and external shocks. The contribution of this research lies in advancing historical scholarships on fiscal policy and defence spending while providing policymakers with insights into alternative financing strategies grounded in past experiences and institutional legacies. © 2025, Universitas Negeri Semarang. All rights reserved.