1. Domestic Isolationism: After World War I, there was a strong sentiment of isolationism in the United States. Many Americans believed that the country should avoid entanglements in foreign affairs and focus on domestic issues. They feared that joining the League of Nations would drag the US into conflicts in other parts of the world.
2. Opposition from President Woodrow Wilson: President Woodrow Wilson was a strong advocate for the League of Nations, but he faced significant opposition from both Republicans and Democrats in the U.S. Senate. Many senators argued that the League infringed on US sovereignty and that the United States should not be obligated to intervene in international disputes.
3. Controversy Over Article 10: One of the most contentious provisions of the League of Nations Covenant was Article 10, which required member states to guarantee the territorial integrity and political independence of all other members. Many Americans felt that this article could potentially obligate the United States to go to war to defend the borders of other countries.
4. Failure to Resolve US Concerns: The United States proposed several amendments to the League of Nations Covenant to address its concerns, but these were not accepted by the other members. This further contributed to the US decision not to join the organization.
5. Emergence of Senate "Irreconcilables": A small group of Senators, known as the "Irreconcilables," led by Senator William Borah, strongly opposed the League of Nations under any conditions. They argued that it violated the US Constitution and would limit US sovereignty.
In summary, the United States refused to join the League of Nations due to a combination of domestic isolationism, opposition from President Wilson's political adversaries, concerns about Article 10, the failure to resolve US reservations, and the presence of strong opposition within the Senate. These factors led the United States to pursue an isolationist foreign policy after World War I.