The 1953 Iranian coup d'état , known in Iran as the 28 Mordad coup d'état ( ) , was the overthrow Change_of_leadership of the democratically elected Change_of_leadership Prime Minister Mohammad Mosaddegh in favour of strengthening Cause_change_of_strength the monarchical rule of Mohammad Reza Pahlavi on 19 August 1953 , orchestrated Arranging by the United States ( under the name `` TPAJAX '' Project or `` Operation Ajax '' ) and the United Kingdom ( under the name `` Operation Boot '' ) .

Mosaddegh had sought to audit Scrutiny the documents of the Anglo-Iranian Oil Company ( AIOC ) , a British corporation ( now part of BP ) and to limit Limiting the company 's control over Iranian oil reserves .

Initially , Britain mobilized its military to seize Hold control Control of the British-built Abadan oil refinery , then the world 's largest , but Prime Minister Clement Attlee opted Choosing instead to tighten Cause_change_of_strength the economic boycott while using Iranian agents to undermine Destroying Mosaddegh 's government .

Judging Mosaddegh to be unreliable and fearing a Communist takeover in Iran , UK prime minister Winston Churchill and the Eisenhower administration decided Deciding to overthrow Change_of_leadership Iran 's government , though the predecessor Truman administration had opposed Agree_or_refuse_to_act a coup Change_of_leadership , fearing the precedent that Central Intelligence Agency ( CIA ) involvement would set .

British intelligence officials′ conclusions and the UK government 's solicitations were instrumental in initiating Process_start and planning Arranging the coup Change_of_leadership , despite the fact that the U.S. government in 1952 had been considering unilateral action ( without UK support ) to assist Assistance the Mosaddegh government .

Mosaddegh was arrested Arrest , tried and convicted Legality of treason by the Shah 's military court .

Other Mosaddegh supporters were imprisoned Arrest , and several received Receiving the death Death penalty .