Abstract

South Asia remains one of the world’s most volatile nuclear flashpoints, with India and Pakistan together possessing an estimated 350–400 warheads as of 2025 and ongoing territorial disputes that could escalate rapidly. A hypothetical regional nuclear exchange involving 100–300 weapons (15–100 kt yields) could produce 50–125 million immediate fatalities and trigger global climatic disruption through stratospheric soot injection. This analytical review synthesizes declassified effects literature, modern modeling (e.g., FEMA, 2022), and empirical data from historical detonations to delineate the three primary hazard phases—intense thermal flash, blast wave, and radioactive fallout