Soon after the Soviet re-entry to Poland in July 1944 in pursuit of the German army, the Polish prime minister from London flew to Moscow along with Churchill in an attempt to prevent the Soviet annexation of Poland in accordance with the Molotov–Ribbentrop Pact signed by the Soviet Union.[33] He offered a smaller section of land, but Stalin declined, telling him that he would allow the exiled government to participate in the Polish Committee of National Liberation.[34] An agreement between the Allies was reluctantly reached at the Yalta Conference where the Soviets would annex the entirety of their Molotov–Ribbentrop Pact portion of Eastern Poland, but would grant Poland part of Eastern Germany in return.[34] Thereafter, eastern Poland was annexed into the Ukrainian Soviet Socialist Republic and the Byelorussian Soviet Socialist Republic.[34]