Question

Why did the United States declare war on Japan?

Answer 1

Hint: On 7 December 1941 Japan attacked the United States naval base at the Pearl Harbour. It was the surprise attack which badly damaged the US naval vessels and caused major destruction and killed 2,403 men. As a consequence of the surprise attack, the United States declared war on Japan on 8 December 1941.

Complete answer: After the surprise attack on Pearl Harbour by the Japanese the American people were surprised, shocked and angered. President Roosevelt addressed a session in which he declared war against Japan. The Japanese attacked the US naval base in pearl harbour because the US had cut the export of oil to Japan in 1941. Japan relied on the US for the export of oil and without it the Navy would not be able to function therefore by attacking pearl harbour they crippled the US Pacific fleet so that there would be no hindrances in the Japanese Navy in the Pacific. The US could not acknowledge the attack as the secret nature of the message took time to be translated, decoded and typed up by high embassy officials who were not able to do these tasks in the available time. Therefore The ambassador could not deliver the attack and the Japanese attacked the pearl harbour before it.
Apart from attacking the US , the Japanese have also attacked the British colonies. Therefore the United Kingdom also declared war on Japan prior to the US did.

Note: The attack on the US naval base at Pearl harbour by the Japanese in 1941 precipitated the entry of the US into World war II. It worsened the relations between the United States and Japan till the end of the second World war.