The threat of the survival of the Soviet Union led the Allies to pursue a "Europe-first" strategy.
Explanation:
Great Britain commanded by Winston Churchill created the plan "Europe First" or "Germany first" because they believed that if Germany was able to conquer the Soviet Union, it was going to become an impenetrable fortress and represented a big danger to them and the rest o the world. Therefore they invited the U.S. to solve the conflict in Europe first. Because they believed japan was far more vulnerable than Germany and that their occupied territories were not such a strong system as the ones of Germany.
