This study aims to analyze the contexts, processes, and consequences of the twelve-day military conflict initiated by the Zionist regime against the Islamic Republic of Iran in 2025. The present research seeks to examine the formation, evolution, and continuation of this event within an analytical framework, linking it to its domestic components, regional drivers, and international contexts. The main research question focuses on the following: What were the causes and consequences of the 12-day war waged by the Zionist regime against Iran? Based on a descriptive-analytical approach and utilizing qualitative methods, data were gathered from documentary, library, and credible online sources. The research hypothesis posits that the 12-day war was the result of a multi-level interaction between threats arising from the structure of the international system—including the diminished role of the US in the unipolar system, the emergence of new powers such as China and Russia, the formation of a new multipolar order, and the intensification of regional rivalries—and the internal political pressures within the Zionist regime and its security elites' perception of Iran's growing threat. In response, Iran's reaction was based on the strategy of "active deterrence," shaped by the perceptions of its elites, domestic considerations, and the level of regional support. The findings of the study indicate that although the Zionist regime attempted to use the war to strengthen its diplomatic position and manage internal challenges, the fluid dynamics of West Asia and Iran's active deterrence capability resulted in this war entailing a degree of failure .