The 1953 Iranian coup d'état was a pivotal event in which the United States and the United Kingdom, through the CIA (Operation Ajax) and British intelligence (MI6), orchestrated the overthrow of Iran’s democratically elected Prime Minister, Mohammad Mosaddegh. The coup occurred on August 19, 1953, after Mosaddegh moved to nationalize Iran’s oil industry, challenging British control over the Anglo-Iranian Oil Company (AIOC).

Mosaddegh's nationalization in 1951 sparked British economic retaliation and diplomatic pressure, which escalated into a joint U.S.-UK plan to remove him, fearing both loss of oil interests and perceived communist influence. The CIA, led by Kermit Roosevelt Jr., used propaganda, bribery, and staged protests to destabilize Mosaddegh’s government. The Shah, Mohammad Reza Pahlavi, initially hesitant, was persuaded to issue a decree dismissing Mosaddegh.

After brief resistance, the coup succeeded, resulting in hundreds of deaths during street clashes. Mosaddegh was arrested, tried for treason, and later placed under house arrest for life. The Shah returned from exile and consolidated power, establishing a pro-Western authoritarian regime backed by U.S. aid and the secret police SAVAK.

The coup is widely seen as having undermined Iranian democracy and fueled long-term anti-American sentiment, contributing to the 1979 Iranian Revolution that overthrew the Shah and established an Islamic Republic. In 2013, the CIA formally acknowledged its role, describing the operation as an undemocratic act of U.S. foreign policy.