The U.S. entered World War I in 1917. Initially maintaining neutrality, the United States was drawn into the conflict due to several factors, including unrestricted submarine warfare by Germany and the interception of the Zimmermann Telegram, which revealed German attempts to coax Mexico into joining the war against the U.S. The American entry provided fresh troops and resources, which proved pivotal in tipping the balance toward the Allies. U.S. involvement marked a significant shift in the war's dynamics, leading to the eventual defeat of the Central Powers in 1918.