Examine this prompt, then type your response below: in the beginning of december 1941, the united states had engaged in some warlike activity but had not yet committed itself to world war ii. prompt: what event caused the united states to declare war? describe this event and explain how it changed public opinion about american involvement in world war ii.

2 words: Pearl Harbor.
California was particularly frightened that the Japanese would attack its coastline. 

Those fears were not groundless. Hawaii is not that far from San Francisco that it couldn't be attacked the same way that Pearl Harbor was.  Air craft carriers were within a good stone's throw from the mainland.

Added to that fact, a huge naval base was in San Diego. What happened at Pearl could happen to San Diego. Fortunately Yamamoto had the sense to realize that all any attack would do would be to awake a sleeping giant. Those were his words. He was educated in America so he knew whereof he spoke. If you are interested in more, Google Admiral Yamamoto.