The Yalta Conference was a meeting of the Allied leaders during World War II in February 1945. It was held in the Soviet Union at the Livadia Palace near Yalta in Crimea. The main participants were U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and Soviet leader Joseph Stalin. The Teheran Conference was a meeting of the Allied leaders during World War II in November 1943. It was held in Tehran, Iran and was attended by U.S. President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and Soviet leader Joseph Stalin.