The U.S. action at Pearl Harbor which ended up helping the Japanese was the fact that the U.S. aircraft carriers assigned to Pearl Harbor were not present when the attack occurred.
This refers to the attack by the Japanese Navy against the US military installations in Pearl Harbor in what was considered a surprise attack.
Hence, we can note that the US action which helped the Japanese and made the attack easier was the fact that the U.S. aircraft carriers assigned to Pearl Harbor were not present when the attack occurred.
Read more about the Pearl Harbor attacks here:
https://brainly.com/question/860420