The Supreme Commander of the Allied Powers (SCAP) was the supreme executive body of Allied Powers. It was created to execute the decisions of the Far Eastern Commission (FEC), the representative entity of Allied Powers, on all matters pertaining to Korea, Japan, and the Pacific region. That is, its role was to enforce the decisions of Allied Powers based on the Cairo Declaration, the Yalta Conference, and the Potsdam Declaration.
In addition, the FEC had no jurisdiction over the SCAP on territorial matters by the terms of reference of the FEC, which read ”FEC shall not make recommendations with regard to territorial adjustment.”Thus, on territorial matters, the SCAP’s legal status and role made it a simple executor of directives by the U.S. government on the basis of the Cairo Declaration, the Yalta Conference, the Potsdam Declaration, and the Japanese Instrument of Surrender.
Following these decisions of Allied Powers and the order by the U.S. government to formalize the decisions, the SCAP enacted SCAPIN No. 677. Although territorial matters had to be defined by the Treaty of Peace with Japan, the SCAP formally “executed” the decisions of Allied Powers (made after the Cairo Declaration) and the directives of the U.S. government through SCAPIN No. 677. This means that although SCAPIN No. 677 was executed, the promise and decision to bring about Korea’s independence by separating Korea (including Dokdo) from Japan and Korea’s governmental and administrative separation from Japan, not to execute SCAP's own will for reasons of convenience to occupy Japan.