why did the japanese attack on pearl harbor
1 The Japanese attacked Pearl Harbor because they knew America was going to have to enter the Pacific Theatre of WWII sooner or later. 2  America's allies, China etc. were being attacked by the Japanese. 3  The Japanese believed it would be a good idea to try and destroy all of the Aircraft Carriers in the Pacific.. When the Japanese decided to attack America, they knew that almost all of the immediate forces were naval. Hence, they decided to bomb Pearl Harbor, as it held the majority of the American naval forces in the Pacific.