Final answer:
The attack on Pearl Harbor led the U.S. to change its isolationist stance, shifting to an interventionist foreign policy during World War II. This shift was evident in the U.S.'s proactive role in the war and its post-war efforts to establish global institutions aimed at maintaining peace and preventing future conflicts.
Step-by-step explanation:
The attack on Pearl Harbor in 1941 marked a pivotal moment in history, leading to the United States' full engagement in World War II. Prior to this event, the U.S. had maintained an isolationist stance in response to the growing threats abroad. However, the aggression by Axis Powers, including the expansionist moves by Japan in Asia and Hitler's invasions in Europe, ultimately drew the U.S. into the conflict. Post-Pearl Harbor, the U.S. foreign policy shifted from isolationism to a more interventionist approach, recognizing the need for active involvement in global affairs to prevent the spread of totalitarian regimes and protect democratic values.
World War II also introduced significant measures on the homefront, such as rationing, propaganda, and war bonds to support the war effort. The concept of the 'Arsenal of Democracy' encapsulated the idea of the U.S. not just as a military power but also as an industrial and moral supporter of the Allies. Post-war, the foreign policy further evolved, leading to the establishment of the United Nations and the onset of the Cold War due to ideological differences with the Soviet Union.