Japan follows up while John Opie's warning stalls

Japan's first observer sent an encrypted report to Isoroku Yamamoto and returned to Tokyo to brief the officer who would lead the Pearl Harbor strike. A larger delegation later inspected the damaged battleships and interviewed Italian commanders and fire-control officers to learn from the defender's perspective. Opie, meanwhile, had witnessed the British pilot briefing, aircraft preparation, returns, and damage evidence. He sent Washington a five-page summary, supporting documentation, and Illustrious's captain's report, then used personal contacts to press the lessons. His request to visit Pearl Harbor and discuss defensive improvements was refused even though the material circulated among senior U.S. Navy offices. A Pearl Harbor commander who separately asked for stronger defences was removed, while congressional and budget pressure are raised only as possible context. Collecting and distributing accurate information did not guarantee that the U.S. Navy would turn it into an operational priority.