Question

Why USA attacked japan?

Answer 1

    First Japan attacked USA at the Port Pearl harbor on the East Coast. Some bombs were dropped destroying some boats, battleships and the coast. It was on Dec 7th in 1941.  Many people were killed. Japan wanted to prevent USA supporting allies with its full force.

   Then President Roosevelt had asked USA's military services to prepare a severe attack on Japan. In April 1942 USA bombers attacked Japan.

   Later on in retaliation USA attacked Japan and dropped the Atomic Bomb. USA took very seriously the attack of Japan. Perhaps that was too much. It should not have been done.  

Answer 2

The declaration of war by the Empire of Japan on the United States and the British Empire was published on December 8, 1941 (Japan time; December 7 in the United States), afterJapanese forces had executed anattack on the United States naval base at Pearl Harbor and attacks on British forces in Malaya, Singapore.