On September 6, US President Truman approved a document titled "US Initial Post-Surrender Policy for Japan".
The document set two main objectives for the occupation: (1) eliminating Japan's war potential and (2) turning Japan into a democratic-style nation with pro-United Nations orientation.
On V-J Day, US President Harry Truman appointed General Douglas Mac Arthur as Supreme Commander for the Allied Powers (SCAP), to supervise the occupation of Japan.
The Soviet Union had some intentions of occupying Hokkaidō.
Had this occurred, there might have eventually been a communist state in the Soviet zone of occupation.
Under the final plan, however, SCAP was given direct control over the main islands of Japan (Honshu, Hokkaido, Shikoku, and Kyushu) and the immediately surrounding islands, while outlying possessions were divided between the Allied Powers as follows: It is unclear why the occupation plan was changed.
Common theories include the increased power of the United States following development of the atomic bomb, Truman's greater distrust of the Soviet Union when compared with Roosevelt, and an increased desire to restrict Soviet influence in East Asia after the Yalta Conference.
was ended by the San Francisco Peace Treaty, signed on September 8, 1951, and effective from April 28, 1952, after which Japan's sovereignty – with the exception, until 1972, of the Ryukyu Islands – was fully restored.