The news of the attack on Pearl Harbor put Hitler in a euphoric mood and declared it a turning point even saying he "had an ally that had not been conquered in 3,000 years." Berlin saw the Lend Lease Act and Americas actions in the battle for the Atlantic as a virtual declaration of war on Germany. Hitler wanted a more aggressive attitude in Japan, wanting them to strike a blow against British colonies while also distracting America.

With the attack on Pearl Harbor and the subsequent declaration of war on America by Germany, Hitler believed that the US would be forced to tie down most of their forces in the Pacific while also being forced to keep supplies flowing to the other Allies via the Atlantic forcing America into a two front war across two massive oceans. On December 8th, Hitler allowed his U-Boats to now attack US shipping which would, in turn, weaken British power against the Japanese and her colonies. This would now give Germany time to focus strictly on the Soviet Union before the inevitable land war with America. Hitler obviously underestimated the power of the US and over estimated the power of Japan. Hitler's fate was now sealed though it did buy Germany time before there ultimate failure in November 1942 with the Stalingrad catastrophe and the invasion of North Africa.

Source: Stephen Fritz- Ostkrieg: Hitlers Was of Extermination in the East

Ian Toll- Pacific Crucible