The 2026 War between Iran, the United States, and Israel, as a geopolitical turning point, has transformed the previous security order of the Middle East and confronted the security architecture of the Islamic Republic of Iran with new challenges, an event that necessitates a review of the country's defense priorities and security doctrine. In this regard, the present study seeks to answer the question of what are the structural effects of this war on Iran's defense doctrine and how to cover regional strategic gaps. According to the research hypothesis, the 2026 War has led to the erosion of traditional balanced patterns and has made the necessity of transitioning from purely hardware security to hybrid deterrence and smart defense diplomacy more apparent than ever before. This study has been conducted using a descriptive-analytical and future-oriented method, based on the theoretical framework of structural realism and the theory of regional security complexes, through strategic data analysis and scenario writing. The findings show that this conflict has led to a change in the balance of power and the need to redefine Iran's strategic depth. Finally, the results of the study show that in order to contain the destructive effects of geopolitical and stabilize its regional position, the Islamic Republic of Iran needs to utilize new capacities in the field of network and economic security and strategic alliance building in the post-war environment.