Why did Stalin not ask at Yalta for a Soviet role in occupying Japan?
Short answerThe Soviet Union was not yet at war with Japan and lacked forces positioned to occupy the home islands, although a longer war could have created an opening in Hokkaido.
NotesAt Yalta, the Soviet Union had not yet entered the war against Japan and was still being courted by the Allies. Moscow also lacked a large force positioned to occupy the home islands. A longer war might have created time for a Soviet foothold in Hokkaido. Japanese leaders therefore had reason to fear the kind of postwar territorial division imposed on Germany.