In recent years, geopolitical changes in the West Asian region, especially following the gradual decline of the role of the United States and the increase of China's influence, have led to a redefinition of the foreign policy priorities of the countries of the region. The Islamic Republic of Iran, as one of the main players in this region, seeks to play an active role in shaping new alliances by utilizing regional capacities. The central issue of this research is what impact has the decline in the presence and influence of the United States and China in West Asia had on Iran's activism in building regional alliances? The research hypothesis is that following the decline in the role of trans-regional powers, Iran is trying to strengthen its influence in the region and redefine the security alliances of the region in its favor by relying on multilateral diplomacy, ideological ties, and common security interests with some regional players. This study, using a descriptive-analytical method and utilizing library and documentary resources, examines Iran's behavioral patterns in the context of interactions with countries such as Iraq, Lebanon, Saudi Arabia, and Qatar, especially after the Islamic Awakening (2010 to date). The findings of the study show that Iran, through strengthening political-security alliances, developing economic and cultural cooperation, and supporting the resistance discourse, has succeeded in creating a level of regional convergence that has led to doubt and a gradual decrease in the effective presence of the United States and a slowdown in China's influence in security areas. However, challenges such as intra-regional competition, sanctions pressures, and distrust among actors remain serious obstacles to the full realization of this strategy.