Intelligence Limitations:
- The United States' intelligence capabilities at the time were not as advanced as they would become during the Cold War. Surveillance and code-breaking technologies were still developing.
- American cryptanalysts were aware that Japan had a sophisticated code system, known as PURPLE, but they had not fully broken the code until after the attack.
- Japan maintained strict secrecy about its military plans, and its diplomatic communications often used ambiguous language.
Isolationist Policies:
- The United States had adopted an isolationist foreign policy in the years leading up to World War II. This policy limited intelligence gathering and cooperation with other countries, including potential allies in the Pacific.
Diplomatic Miscalculations:
- American officials were engaged in diplomatic negotiations with Japan in the months leading up to December 7. They received assurances that the Japanese government was seeking a peaceful resolution to tensions in the Pacific.
- However, some within the U.S. government, including President Franklin Roosevelt, suspected that Japan might take aggressive action. Yet, they did not anticipate an imminent attack on Pearl Harbor.
Lack of Specific Warnings:
- Despite indications of Japanese expansionist intentions, there was no clear or conclusive intelligence indicating an immediate threat to Pearl Harbor.
- The Japanese attack plan was carefully crafted to achieve strategic surprise, and the Japanese navy successfully maintained a radio silence during its approach to Hawaii.
Failure of Reconnaissance:
- American military reconnaissance flights in the days leading up to the attack did not detect the Japanese fleet approaching Hawaii.
It's important to note that while the attack itself was a surprise, tensions between Japan and the United States had been rising for several years. The attack was the culmination of years of political, territorial, and economic conflicts between the two nations in the Pacific region.