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 '' ) .