The new Polish-Soviet border was internationally recognized as well as ratified by the League of Nations . The peace agreement remained in place throughout the interwar period . The borders established between the two countries remained in force until the outbreak of World War II , and the 17 September 1939 Soviet invasion of Poland . They were later redrawn during the Yalta Conference and the Potsdam Conference on the insistence of Joseph Stalin
Yalta Conference
Yalta Conference
Western Belorussia