'Cairo Three' was the Allied cover designation of the inter-Allied 'Eureka' conference held in Tehran, the capital of Iran, between President Franklin D. Roosevelt, Prime Minister Winston Churchill and Premier Iosif Stalin (28/30 November 1943).

This conference was held to decide on the Allies' priorities after the successful invasion of Italy, and the conclusions reached were the abandonment of 'Buccaneer', the application of increased pressure in Italy (up to a proposed stop line between Livorno on the western coast and Rimini on the eastern coast) in order to prevent the Germans from withdrawing forces that could then be sent to the Eastern Front, the timing of 'Overlord' moved to the beginning of June 1944 so that it would coincide with the opening of the Soviet 'Bagration' summer offensive of that year, and the launching of 'Anvil' (later 'Dragoon' ) in conjunction with 'Overlord' to pin as many German forces in France as possible. Preliminary agreement was also reached between the 'big three' on the partition of post-war Europe into spheres of influence that would greatly enhance the political, economic and military strength of the USSR.