The Anglo-Soviet invasion of Iran began in August 1941, primarily aimed at securing British and Soviet interests in the region against the backdrop of World War II. Iran, under the rule of Shah Reza Pahlavi, had declared neutrality; however, the Allies were concerned about Nazi Germany's growing influence in the country. With threats to vital oil fields and supply routes, the invasion was launched by British and Soviet forces. By September 17, 1941, Soviet troops made significant advances, ultimately entering Tehran, the capital of Iran.

The occupation of Tehran had immediate military and political implications. The city was strategically important due to its location and resources, which were essential for the Allies’ war effort. The entry of Soviet forces into this capital not only boosted the morale of the coalition but also underscored the urgency of maintaining stability in the region as the war escalated. Following the occupation, Reza Pahlavi was deposed, and his son, Mohammed Reza Pahlavi, was installed as the new Shah, which altered the political landscape of Iran permanently.

The geopolitical ramifications extended beyond Iran itself. Post-invasion, Iran became a logistical hub for the Allies, facilitating supplies and resources to the Soviet Union via the Persian Corridor. This event marked a significant shift in Middle Eastern politics, aligning Iran more closely with Allied powers during and after the war, setting a foundation for future foreign relations in the region. The occupation consequently led to increased Western influence in Iran, with repercussions that would manifest in the political environment for decades.