Question

why did the united states enter into world war ii? because they felt obligated to help their allies. because japan bombed pearl harbor.

Explanation:

While the U.S. had growing ties to Allied powers, the direct, immediate trigger for U.S. entry into World War II was the surprise Japanese attack on the U.S. naval base at Pearl Harbor on December 7, 1941. The U.S. declared war on Japan the following day, and Germany and Italy then declared war on the U.S.

Answer:

Because Japan bombed Pearl Harbor.