Answer:
The United States did not ratify the treaty and join the League which was a key reason for its failure
Step-by-step explanation:
League of Nations was established at the end of the World War 1 as an international peacekeeping organization with the aim to disarmament, preventing further wars, settling dispute between countries and improving global welfare. However, the League of Nation fail in achieving it aims and the failure of League of Nation was the main reason for the outbreak of another war because they failed to resolve the major political dispute this leads to the exposed of their weakness
The League of Nation was an idea of President Woodrow Wilson during the course of First world war, However the public voted against it, the United State Senates did not ratify to join the League which was the key reason for its failure since United State was a key player for the Europeans allied.