World War II led Iran to engage in global events unwittingly and was occupied by the three powers; however, with the end of the war and the non-evacuation of the Soviet forces from Iran, the Cold War first sparkles were struck between the two ideological poles, the Soviet Union and the United States. By pressing Iran, the Soviets demanded an oil concession from the Northern provinces of Iran. In contrast, the US with the policy of preserving Iran in the Western countries orbit, stood in front of the Soviet Union. Although many research have cited the US ultimatum to the Soviet Union for evacuating Iran as the main cause of Soviet withdrawal from Iran, the reviews showed that such an ultimatum had no historical validity; The question then is, what tools and tactics did the US use to accomplish its goal of expelling the Soviet Union from Iran and keeping Iran in the orbit of liberalism. We have attempted to answer this question by using a historical method that is based on description and analysis. We examined the US State Department documents. The findings showed that US by using two types of international instruments, such as the Security Council and the alliance with the UK, and domestic instruments such as cooperation with the Shah and the National Parliament, tried to restrict the Soviet Union.