Final answer:
The League of Nations was aimed at promoting collective security post-WWI, but it had minimal impact on U.S. isolationism due to America's non-participation.
Step-by-step explanation:
The League of Nations, established by the Treaty of Versailles in 1919, played a pivotal role in global politics following World War I. While the League notably aimed to promote collective security and prevent military conflicts, it had limited impact on the United States' shift toward isolationism during the interwar period.
President Woodrow Wilson's vision for international relations and a new world order through the League of Nations was intended to promote peace and deter aggression. However, the U.S. Senate's refusal to ratify the Treaty of Versailles ultimately resulted in America's absence from the League.
As a consequence, without active U.S. participation, the League's influence on American foreign policy was minimal. America’s shift toward isolationism was largely a response to domestic concerns and a desire to avoid the entanglements of European politics.