The Soviet invasion of Poland of 1939 was a military operation that started on September 17, 1939, during the early stages of World War II, sixteen days after the Nazi German attack on Poland. It ended in a decisive victory for the Soviet Union's Red Army. On August 23, the Soviets signed the Molotov–Ribbentrop Pact with Nazi Germany, and on 1 September, the Germans invaded Poland from the west. The Red Army invaded Poland from the east on 17 September after several calls by Germany to do so. The Soviet government announced that it was acting to protect the Ukrainians and Belarusians who lived in the eastern part of Poland, claiming that the Polish state had collapsed in the face of the German attack and could no longer guarantee the security of its own citizens. The Red Army quickly achieved its targets, meeting only light Polish resistance. 6,000 to 7,000 Polish soldiers died in the fighting, and 230,000 or more were taken as prisoners of war. The Soviet government annexed the territory newly under its control and in November declared that the 13.5 million Polish citizens who lived there were now Soviet citizens. The Soviets quelled opposition by executing and arresting thousands. During the existence of the Polish People's Republic, the invasion was considered a delicate subject, almost taboo, and was often omitted from official history in order to preserve the illusion of "eternal friendship" between members of the Eastern Bloc.