I base this question on some reading I did decades ago on this matter. I first read of an encounter in the deserts of Sonora of a Japanese recon party confronted by the Pierce-Hornaday USGS Expedition in 1907 . Then I met a man in his eighties (about 1991) who was hired to help the US Army in relocating Japanese-American families in the Stockton-Modesto area in the spring of 1942. When he questioned the harshness with one family, the army officer directed him to climb up and look into an artesian well cistern (they generally stand about 15-20 feet high) and he saw a small searchlight with two auto batteries. The officer said it was part of a signal system that vectored from the coast to Mather Field (AFB) near Sacramento. This is a second hand tale and yes, it is not evidence, and perhaps unverifiable. Going back centuries nations established deep-cover agents in rival nations , including the United States. Nothing I heard on the matter indicated more than a few dozen people involved. Any truth to this or its it not verifiable?