 Complete the following phrase:  Worried by the possibility of American support after their entry into the war following the Attack on Pearl Harbor, and a potential Anglo-American invasion on the Western Front in 1942 which would not actually happen until 1944, Hitler shifted his primary goal from an immediate victory in the East, to the more long-term goal of securing the southern Soviet Union to protect oil fields vital to a long-term German war effort. The German southern campaign began with a push to capture the Crimea which ended in 