In March 1939, Hitler occupied the remainder of Czechoslovakia, which now took in a further 180,000 Jews, while in May 1939 the British issued the White Paper which barred Jews from entering Palestine or buying land there. Following their occupation of Poland in late 1939 and invasion of Soviet Union in 1941, the Germans embarked on a program of systematically killing all Jews in Europe. In this, the Nazis had local assistance in at least some cases.