Final answer:
In the 1930s, isolationist sentiment was prevalent in the U.S., reinforced by the Neutrality Acts aimed to keep America out of foreign wars. The mood began shifting as threats rose globally, but the U.S. maintained neutrality until the attack on Pearl Harbor in 1941.
Step-by-step explanation:
Isolationism During the 1930s in the United States
During the 1930s, isolationist sentiment was prevalent throughout the United States as the nation grappled with the effects of the Great Depression and retained fresh memories of the losses from World War I. The public and Congress were significantly influenced by anti-war sentiment, as evidenced by the legislation of the Neutrality Acts between 1935 and 1937, which aimed to prevent the U.S. from engaging in foreign conflicts.
The pacifist mood began to wane by 1938 as global tensions rose with the aggressive actions of Japan, Germany, and Italy. Nevertheless, the U.S. policy remained largely noninterventionist, in part due to economic self-interests and ethnic influences, such as the Irish Americans' opposition to England and German Americans' sympathies for Germany.
Although President Roosevelt privately indicated a desire to support allies like Britain and France, the official stance of the U.S. government leaned towards neutrality, abiding by the established neutrality laws.
Ultimately, however, the direct attack on Pearl Harbor on December 7, 1941, served as a turning point, compelling the U.S. to enter World War II and marking the end of its isolationist period. This shift showed that while the U.S. sought to avoid another costly conflict, it could not remain removed from global affairs when directly threatened.