Why did the US shift from a policy of neutrality to a policy of engagement?

The U.S. shifted from a policy of neutrality to engagement primarily due to the growing realization that global events directly impacted national security and economic interests. The rise of aggressive totalitarian regimes in Europe and Asia during the 1930s, coupled with the attack on Pearl Harbor in 1941, underscored the need for active participation in international affairs. Additionally, the U.S. aimed to promote democracy and prevent the spread of fascism and communism, leading to a more interventionist foreign policy. This shift ultimately laid the groundwork for the U.S. to emerge as a global leader in the post-World War II era.