Japanese Spies on the West-Coast (Ken Magazine, 1939)
A 1939 magazine article that reported on the assorted activities of Japanese spies operating around the Tijuana/San Diego region (their presence was well-documented by the Mexican military in addition to the F.B.I.).
A year and a half before the Pearl Harbor attack, Naval Intelligence sold a Japanese agent some bogus plans of the naval installation – more about this can be read here.