Final answer:
American foreign policy transitioned from isolationism in the early 20th century to imperialism in the 1890s, and then to active global engagement post-World War II, cementing the U.S. position as a superpower. Significant moments in history, like the Gulf War and Balkan conflicts, reflect the shifts in policy from avoiding foreign alliances to embracing a role of global leadership.
Step-by-step explanation:
American foreign policy has significantly changed over time, especially in response to global events in Europe and Asia. The 1890s were a pivotal era as the United States started to engage in imperialism, which meant extending its political, economic, and military influence over other nations. Following an isolationist period after World War I, World War II heralded a new phase where the U.S. rose to become a superpower, embracing a policy of active engagement, especially during the Cold War. This marked a departure from the isolationism of the 1920s and 1930s, towards a more interventionist stance that shaped global politics, up until the end of the twentieth century.
Post World War II, American involvement in global affairs grew exponentially as it took on a leadership role in Europe and the Pacific, steering away from its previous noninterventionist approach. The U.S. recognized the need for perpetual engagement to maintain global stability in light of weakened traditional powers. Between 1980 and 2000, American foreign policy continued to evolve with its approach becoming more focused on diplomatic and military involvement in international crises, such as the Gulf War and the Balkan conflicts, highlighting the shift from isolation to global engagement.