To me, the biggest "event" of the conference in Teheran was Stalin's promise to jon the war against Japan after the war in Europe was over. The Americans, especially, thought this was a good idea but it turned out not to be.
Late in the war, Stalin kept this promise. In my opinion, when he did that he helped make the US hurry to get the war over with. The US did not really want the Soviets to take more territory in Asia because they did not want the Soviets to have more power after the war (looking towards the Cold War). This may have played a role in the dropping of the atomic bombs -- the need to end the war quickly may have helped lead to this.
Teheran Conference took place from Nov. 28 to Dec. 1, 1943, in Teheran, Iran's capital. It was the first meeting of the main Allied leaders during World War II. These leaders were Prime Minister Winston Churchill of Great Britain, President Franklin Delano Roosevelt of the United States, and Premier Joseph Stalin of the Soviet Union. It was also the first summit conference between the heads of the Soviet Union and the United States.
The most important decision taken during the conference which had a major impact on the course of war was the decision that the United States and Britain would launch an invasion of France in 1944. Other decision taken during the conference included Soviet Union agreeing to enter the war against Japan after Germany's defeat, and redrawing Polish-Soviet border to add territory to the Soviet Union that had been part of Russia before World War I began in 1914. Plans for establishing a United Nations organization, and for dividing and disarming Germany were also discussed during this conference. The Teheran Conference paved the way for subsequent agreements at the Yalta Conference in 1945.
In an apparent Examination of the Terehan Conferance, seemingly a Definite agenda was being related by all parties involved in the Dialogue. This Conference Had some Contingent bearing on the Yalta Conference, as it Firmly Entrenched Winston Churchills' stance as a strong unilateralist. One sees this Evident in His Approaches to His fellows in Attendance. The position Stressed By President Franklin Delano Roosevelt in as Much as It Had a Definite Effect on the Outcome of The War...and Overtones into his Sucessor Harry Trumans' Administration. Even Though Roosevelt was Seen as Being " Globally Isolationist " in some of His Thinking, later Reflected in Policy of Key Issue...He Was Wise in Affirming that He Needed the Kremlin, Premier Joseph Stalin and the Might of Russia and Her Soviet Block "Allies" to Win the Fighting on the EASTERN Fronts' Offensive.
Furthur, we now Know Due To Agents In The American Defensive Initiative (then remembered as the Manhattan Project), A Large Compromise of our National Defense was afoot. Due to 'MOLES', Such as Harvey Greenglass (U.S. Army Intellegence ) , Claus Fuchs, (Vichy/ France) John Hall, ( The United Kingdom) and Julius and Ethel Rosenberg( Immigrants from 'Palestine' then becomming American Citizens) Had Tipped off Premier Joseph Stalin and He "Brought with Him and His Coherts" The Total Disclosure from these Moles.. Kept in Silence from all of the Soviet Representatives, having allowing Premier J.Stalin then a Parody of Strategic Knowledge opertaining to the Manhattan Project...for which would Not be known until the Release of the K.G.B.s' Vinona Transcripts in the 1980s'.