The CIA and MI6 help to overthrow the government of Mohammad Mosaddegh in Iran and reinstate the Shah Mohammad Reza Pahlavi.

In August 1953, the United States’ CIA and Britain’s MI6 played central roles in the overthrow of Iranian Prime Minister **Mohammad Mosaddegh**, one of the most consequential events in modern Iranian history. Mosaddegh had become prime minister in 1951 and strongly supported the nationalization of the **Anglo-Iranian Oil Company**, which was largely controlled by British interests. Britain responded with an economic blockade and other efforts to weaken Mosaddegh’s government. After attempts to reach a settlement failed, British intelligence began planning his removal. The United States initially showed reluctance, but the administration of President Dwight D. Eisenhower became increasingly concerned that political instability in Iran might strengthen the communist Tudeh Party and expand Soviet influence during the Cold War.

The CIA and MI6 therefore cooperated in a covert operation known in the United States as **Operation TPAJAX**, or simply Operation Ajax. Intelligence operatives worked with Iranian political figures, military officers, royalists, journalists, and other groups to undermine Mosaddegh and build support for **Shah Mohammad Reza Pahlavi**. The campaign included propaganda, political pressure, the organization or encouragement of demonstrations, and payments to influential Iranians. An initial attempt to remove Mosaddegh on August 15–16 failed, causing the Shah to flee the country. However, unrest continued, and on **August 19, 1953**, pro-Shah forces and military units gained control of key locations in Tehran. Mosaddegh’s residence was attacked, his government collapsed, and General **Fazlollah Zahedi**, supported by the coup plotters, became prime minister.

The Shah soon returned to Iran, and the coup significantly strengthened his position, allowing him to develop an increasingly authoritarian monarchy that remained in power until the **Iranian Revolution of 1979**. Mosaddegh was tried for treason, imprisoned for three years, and then kept under house arrest until his death in 1967. Although Cold War concerns were important to American involvement, British interests were also strongly connected to regaining access to Iranian oil. The coup left a lasting legacy of resentment toward Britain and especially the United States among many Iranians, contributing to the deep mistrust that shaped relations after 1979. Decades later, declassified documents provided extensive evidence of the CIA’s role in planning and supporting the operation, making the 1953 coup a prominent example of Western covert intervention in another country’s political affairs.