Just 30 years later, the Jews were once again targeted and killed during the Holocaust when the Nazis occupied Ukraine. During the war, a total of 1.5 million Ukrainian Jews were killed, leaving only 40% of the Jewish population prior to the war. In 1939, when Western Ukraine was taken over by Germany, the Jews were put into ghettos and later sent to death camps where they were killed. Additionally, the Einsatzgruppen, the mobile killing units, was responsible for the mass murder of up to a million Ukrainian Jews. On the other hand, Jews living in areas annexed by the USSR did not come into contact with the Nazis, but they were forced to undergo Sovietization.