What event caused the US to declare war on the axis powers of Japan Italy and Germany?

Answer 1

There was no single event, it was a chain of events.Here is the sequence of events:

1. US embargoed scrap metals and aviation gasoline sales to Japan.
2. Japan's attack on Pearl Harbor (partially for military reasons and partially in retaliation for the US trade embargo).
3. US declared war on Japan.
4. Hitler declared war on the US in support of Japan (this was a big mistake).
5. Mussolini declared war on the US in support of Nazi Germany and Japan.
6. US declared war on Nazi Germany and Fascist Italy.

Answer 2

Pearl Harbor which happened on December 7, 1941 is what brought the US into World War 2 and why it declared war on Japan and Germany.

Answer 3

The Japanese bombed our Navy base at Pearl Harbor, Hawaii on December 6, 1941.

Answer 4

The japanese attack on Pearl Harbor