Not saying we WERE cowardly, just that we were perceived as such by the Japanese. If they had employed their submarines in the same way we did, the war could very well have lasted longer. NOT a good thing.
The japs were viciously evil, but they were not stupid...
Almost 100% of all their war-fighting raw natural resources had to be imported...
They focused on our fleet because there were no long columns of supply ships bringing required raw war-fighting resources to the American mainland...
The few that did exist were being handled by the German U-Boats quite handily as they came from South America through the Caribbean to the U.S.
The U.S., way back then, had massive homeland resources of raw materials, the planet's largest manufacturing base, and hard-working patriots who loved their country...
All of these have been deliberately eliminated in the past 50 years...