The Iranian revolution of 1979 that occurred as a result of Ayatollah Rouhoullah Khomeini leading the overthrow of Shah's regime is an Islamic revolution. The revolution was viewed partially as a way for Iranian conservatives to counter the Pahlavi who was so attached to the West, especially the United States. Before the Revolution, all foreign intelligence services believed that the Shah was strong and decisive and would not shy away from what he needed to do. The role of nationalism and its twin in Iranian domestic politics, anti-Americanism, was missed and misunderstood by the CIA station in Tehran. The CIA could not foresee the Revolution because they had no connection with the streets, bazaars, and mosques. After taking the oath of office as president, Ronald Reagan ordered a covert action directed by National Security Council (NSC) to support Iranian paramilitary and political exile groups. This study aims to develop our understanding of how a country's foreign policy and its decisionmakers was affected by an intelligence agency.