What caused the U.S to join WW1?

Answer 1

The U.S. joined World War I primarily due to unrestricted submarine warfare by Germany, which threatened American lives and commerce, exemplified by the sinking of the Lusitania in 1915. Additionally, the interception of the Zimmermann Telegram in 1917, in which Germany proposed a military alliance with Mexico against the U.S., further inflamed public opinion. Economic ties to the Allies and the desire to safeguard democracy also motivated U.S. involvement in the conflict.