The East Asian climate-warfare nexus underwent a paradigm shift across pre-industrial and industrial eras.

East Asia, marked by exceptional climatic diversity, high population density and rapid development, faces severe transboundary climate-security risks under anthropogenic climate extremes. Understanding the climate-warfare nexus-especially by comparing causal pathways under natural versus anthropogenic forcing-is critical for conflict prevention, yet quantitative comparisons across these regimes remain lacking. This study examines the climate-warfare relationship in East Asia from 1400 to 1980 CE using correlation, regression and causal analysis of climate, population, land use and warfare data. Results uncover a paradigm shift: from a slow, feedback-driven Malthusian system in the pre-industrial era to a rapid, socioeconomically-mediated resilient system in the industrial period. Crucially, temperature's causal role shifted from a linear driver of warfare to a non-linear "threat multiplier", indicating that climate-warfare pathways are not static but transform over time. This evolution-from a vulnerable system trapped in crisis feedback loops to a resilient one capable of absorbing shocks-implies that under modern anthropogenic warming, climate anomalies may interact with social systems in non-linear and potentially abrupt ways, necessitating advanced strategies to mitigate future climate-driven conflict risks. By integrating causal analysis, this work addresses key research gaps and offers new insights into the evolving nature of climate-warfare nexus.