Of all things, it was the entry of the United States into the war that prompted Hitler to move the Holocaust into high gear. Now that the Americans were in it, the usefulness of the remaining Jews as hostages was at an end, and Hitler saw no reason to delay the complete destruction of the Jewish race – all the ones he could get his hands on, at least – a moment longer.
This announcement was made to a group of fifty or so of the highest ranking Nazis, chiefly the politicians and bureaucrats who formed the Third Reich’s top echelon, whom Hitler had summoned to a meeting in the Reich Chancellory. Himmler, Goebbels and Bormann are all known to have attended the meeting. Moreover, documents related to this meeting – including Goebbels’ diaries – make it clear that the plan to exterminate the Jews was not carried out without Hitler’s knowledge or responsibility, but that he was an enthusiastic proponent and participant of it. The following year, 1942, would account for almost half the total Jewish deaths in the Holocaust all by itself.
By Bundesarchiv, Bild 183-H1216-0500-002 / CC-BY-SA, CC BY-SA 3.0 de, Link
As mentioned in: