On 28 November 1943 the Tehran Conference opened: Roosevelt, Stalin and Churchill met - for the first time since the beginning of the Second World War - in the Iranian capital to discuss the future of the conflict and various political issues, in anticipation of the post-war phase.
The main issue addressed was purely strategic and concerned the opening of a western front: Stalin had been asking for the launch of this operation for some time, to alleviate the pressure on the Soviet army in the east; to facilitate military action, he undertook to launch a further offensive in the east, in order to commit resources of the Nazi troops. After the landing in Sicily, in fact, there was no last line of combat to encircle Hitler's Germany and inflict the final defeat. It was decided, therefore, to begin Operation Overlord in May of the following year, with a landing in France from the English Channel. In addition, the Soviet Communist Party Secretary said he would declare war on Japan, the third Axis country, once Germany was neutralized.
The three leaders, however, not only discussed military strategies, but also spoke, with foresight, about the world political order for the period after the war. Stalin, in particular, claimed territorial concessions (in part, then, obtained) and the three discussed the possible division of Germany, to avoid future expansionist ambitions and aggressive warfare. Another topic discussed by Stalin and Roosevelt was linked to the organization that the United Nations should have, which, in the American plans, should be controlled by four major powers (United States, Soviet Union, Great Britain and China - the final result, as is known, was consistent with this vision: the four countries, with the addition of France, are still the only permanent members of the UN Security Council). Finally, the three leaders pledged to support Iran and defend its independence and territorial integrity.
The events that followed the Conference were fundamental to the outcome of the war and the next phase: the Normandy landing, the central issue, took place in June 1944 and was decisive for the victory of the Allies. The decisions taken in Tehran were then finalized in the following conferences of Yalta (February 1945) and Potsdam (July-August 1945), while the Charter of the United Nations, which outlined the principles and institutional structure that we know today, was adopted on June 6, 1945. The Soviet Union, in August 1945, finally declared war on Japan, even if the release of the American atomic bombs on Hiroshima and Nagasaki led to a sudden conclusion of the conflict and to the surrender of the Asian Country shortly afterwards.