Potsdam Agreement applies to jurisdiction Soviet occupation zone of Germany
Overview
After the end of World War II in Europe (1939–1945), and the decisions of the earlier Tehran, Casablanca and Yalta Conferences, the Allies assumed supreme authority over Germany by the Berlin Declaration of June 5, 1945. 
At the Potsdam Conference the Western Allies were presented with Stalin's fait accompli awarding Soviet-occupied Poland the river Oder as its western border, placing the entire Soviet Occupation Zone east of it (with the exception of the Kaliningrad enclave), including Pomerania, most of East Prussia, and Danzig, under Polish administration. The German population who had not fled were expelled and their properties acquisitioned by the state.  President Truman and the British delegations protested at these actions. 
The Three Power Conference took place from 17 July to 2 August 1945, in which they adopted the Protocol of the Proceedings, August 1, 1945, signed at Cecilienhof Palace in Potsdam. The signatories were General Secretary Joseph Stalin, President Harry S. Truman, and Prime Minister Clement Attlee, who, as a result of the British general election of 1945, had replaced Winston Churchill as the UK's representative. The three powers also agreed to invite France and China to participate as members of the Council of Foreign Ministers established to oversee the agreement. The Provisional Government of the French Republic accepted the invitation on August 7, with the key reservation that it would not accept a priori any commitment to the eventual reconstitution of a central government in Germany.
James F. Byrnes wrote "we specifically refrained from promising to support at the German Peace Conference any particular line as the western frontier of Poland." The Berlin Protocol declared: "The three heads of government reaffirm their opinion that the final delimitation of the western frontier of Poland should await the [final] peace settlement." Byrnes continues: "In the light of this history, it is difficult to credit with good faith any person who asserts that Poland's western boundary was fixed by the conferences, or that there was a promise that it would be established at some particular place."