No Japanese Spies in America in WWII
The US built huge air bases in three islands in the Pacific for bombing the Empire of Japan after US fleets and troops took over Saipan, Tinian, and Guam in 1944.
And in August 1945, a small air squadron of B29 bombers attacked Hiroshima and Nagasaki with atomic bombs, which led to the surrender of the Empire on August 15.
But couldn't the Imperial military notice anything foretelling the atomic bomb attacks? No, they could not effectively, but...
A special intelligence unit of the Imperial Army was intercepting radio communications between US air planes and air bases in the Pacific Ocean. The unit had listening facilities around Tokyo. They could capture radio waves transmitted even by B29s flying around Saipan, Tinian, and Guam.
At the time Japanese intelligence officers could not decipher coded signals the US military was then using, though they could decode US diplomatic coded messages. However, they discovered that B29s used specific ID numbers like V400, V500, and V700. It looked like B29 bombers were divided into the three major formations: V400, V500, and V700. Each formation seemed to be using a specific air base in either of the three islands: Saipan, Tinian, and Guam. For example, if a B29 radioed a signal 15V500, the bomber was the 15th plane of the V500 air battalion.
In this way, Tokyo comprehended how many B29s were stationed in each of Saipan, Tinian, and Guam in early 1945. But one day in May 1945, the intercepting unit detected a very strange radio signal from a B29 flying from Hawaii to Tinian, which had never happened before. The B29 sent a message directly to Washington DC. And this B29 expressed itself as XXV600. It belonged to a new air battalion.
However, as time went by and more radio interceptions were made, it became clear that this air battalion had only 10 or so B29s, while each of other battalions had more than 120 B29s. Japanese intelligence officers paid their attention to movements of this V600 unit. V600's B29s were only training themselves sometimes flying near to Japan over Iwojima. Even in such drill flyings, they flew only in a single- or a few-plane formation. They didn't join air raids being pushed forward by other B29 squadrons.
Then one day, Japanese radars and radio interception facilities detected one B29 of the V600 battalion approaching Japan. It was flying toward the Inland Sea of the Japanese Archipelago. When B29s came to bomb Japanese cities on the Inland Sea regions, between Northern Kyusyu and Osaka, they usually came from the west. But in the sky over the straight between the western end of the Inland Sea and the Pacific Ocean there were no other B29s. Japanese intelligence officers in radio facilities around Tokyo thought it was funny. Then several hours later, they were reported that a few B29s that invaded into the sky over Hiroshima, on the Inland Sea, from the eastern direction dropped a new-type of bomb that destroyed most of Hiroshima City.
One of Japanese intelligence officers then remembered that he read a report, weeks before, of intercepted American news that one of US newspapers reported that an important experiment was successfully completed in New Mexico. It must have been an atomic bomb test.
It is true as the US Government sent almost all of Japanese Americans and Japanese living in the mainland US to concentration camps in the wake of the Pearl Harbor Attack of December 1941, there was none in the mainland US that would spy on US military movements for the Empire of Japan.
But if the Imperial Japanese Army/Navy had had such concrete information that V600 B29s were for the atomic bomb attack mission, they should have sent scores of zero-fighters to the sky over Hiroshima to shoot down these 2 to 3 B29s venturing into Hiroshima with the atomic bomb.
However, there were none in the mainland America that would work for Japanese to spy on the US Government in WWII.
US B29 bombers in Tinian Island in WWII
**** **** ****
Mar 6:27 And immediately the king sent an executioner, and commanded his head to be brought: and he went and beheaded him in the prison,
Mar 6:28 And brought his head in a charger, and gave it to the damsel: and the damsel gave it to her mother.
Mar 6:29 And when his disciples heard of it, they came and took up his corpse, and laid it in a tomb.
Mar 6:30 And the apostles gathered themselves together unto Jesus, and told him all things, both what they had done, and what they had taught.