what event sparked american involvement in ww2
The main event that led the US to entering ww2 was Japan bombing  Pearl Harbor. The day after the bombing u.s. joined the war   On December 7, 1941, the Japanese Navy lau â¦ nched a surprise attack  on the naval base at Pearl Harbor, Hawaii.lthough the growing peril of Britain worried many, including Roosevelt, it was not until the US was directly attacked at Pearl Harbor that public and political opinion turned in favor of war with the Axis.