If you research the presidency of Franklin Roosevelt, 1932-1945, you will find that he and the U.S. government were aware of many conflicts between Japan and the United States, which, escalated until the fateful Pearl Harbor attack on 12/7/41. The conflicts were focused on territorial issues, for example, the U.S. had a strong influence in the Philippines and islands in the South Pacific. Japan was interested in gaining influence in these areas since they believed they would be beneficial to them geographically, and the U.S. did not have sufficient reasons to have authority in regions so close to Japan. The U.S. was suspicious of potential Japanese aggression in this reason, but few thought it would actually embark on a military operation as drastic as the bombing of a U.S. military base. This is a rough summary of the situation prior to 1941, but you should consult more comprehensive sources to truly understand the specific issues.