Final answer:
Europe and the U.S. failed to effectively respond to Nazi aggression, limiting Jewish refugee immigration and adopting appeasement policies that allowed Nazi expansion.
Step-by-step explanation:
Leaders in Europe and the United States failed to adequately respond to Nazi Germany's military aggression and the persecution of Jews and other groups prior to and during World War II. Despite clear signs of hostilities and emerging reports of atrocities, measures taken were often insufficient or delayed. U.S. State Department policies in the 1930s made it difficult for refugees, including Jews, to enter the United States, often citing economic hardships of the Great Depression to discourage immigration. After the violent night known as Kristallnacht and the fruitless Evian Conference, numerous Jewish refugees were still denied asylum. The tragic voyage of the MS St. Louis exemplified this failure when over nine hundred Jewish refugees were turned away, forcing the ship to return to Europe, with many passengers later perishing in the Holocaust. Likewise, European leaders, including Britain and France, largely pursued a policy of appeasement, allowing Hitler's expansionist strategies to go unchecked and enabling the Nazi regime to fortify its power.