Jerusalem fell to Israel in the Arab-Israeli war (1967).
Soviet intervention in Poland at the time of German invasion of Poland in 1939 spooked Hitler; this development led to division of Poland between the Soviet and German forces for a while.
Hitler was not comfortable with the aforementioned statusquo.
Hitler also noticed that the Soviets suffered great losses in taking over Finland (1939 - 1940), and had a low opinion of Soviet military machine since. He thought that the Wehrmacht would roll over USSR but his biggest blunder was to overlook how USA will respond to his moves. USA not only came to the aid of USSR (i.e. Allied Lend Lease program) but opened a major front against the Wehrmacht in Africa in 1942 and US-backed forces advanced all the way to Italy by 1943. British breakthrough in infiltrating German communication techniques (i.e. Enigma Code) also facilitated these advances.
American interventions prevented the Wehrmacht to achieve breakthroughs in the Eastern front in later years because the Germans had to divert precious resources to war against US-backed forces towards Africa and then Italy. Final thrust of US-backed forces against the Wehrmacht came in Normandy in 1944, and it was game over for the Nazi regime at this point.