On the 66th anniversary of the bombing of Hiroshima, NHK broadcast a fascinating look at what the Japanese government knew—or should have known—about the impending destruction of Hiroshima and Nagasaki. The surprising answer is they knew—or should have know—a lot.

Combing through the archives of Japan's signals intelligence service, NHK unearthed the original log books and taped interviews with key personnel made after the war. What becomes clear is that the analysts "on the ground" had collected all the pieces, but nobody in the chain of command put the puzzle together.

Here is what NHK found about what they knew they didn't know at the time:

• The Japanese government initiated its own atomic bomb program (promising to destroy New York), but canceled it soon afterward, concluding that it was impossible and the American project would never succeed.
• Although they couldn't read the encrypted messages, Japan's signals intelligence service identified and logged the call sign prefixes of B-29s flying out of the Marianas Islands, and could roughly predict their destinations.
• Early in 1945, they detected a new call sign prefix (tagged "V-6") being used by a curiously small air wing comprised of only a handful of planes. These planes flew a large number of training missions from Tinian Island.
• The Supreme War Council was aware of the atomic bomb test in Alamogordo, New Mexico (perhaps through their Soviet contacts), but assumed it was a new kind of conventional explosive.
• On 6 August 1945, a single B-29 using a V-6 call sign was detected approaching Japan. The signals intelligence service sent this unusual information up the chain of command. No action was taken.
• That B-29 was the Enola Gay.
• A day later, the Supreme War Council announced that Hiroshima was destroyed by a small but powerful conventional bomb. When it became clear the bomb was atomic, they said it was unlikely the U.S. had more than one.
• The signals intelligence service requested permission to order evacuations if another B-29 using a V-6 call sign entered Japanese air space. Permission was never granted.
• On 9 August 1945, a B-29 using a V-6 call sign was detected approaching Kyushu. This information was sent up the chain of command. No action was taken.
• That B-29 was the Bockscar.
• At least five hours elapsed between the time the V-6 call sign was logged and Nagasaki was bombed. The Bockscar was delayed by a late rendezvous, then by cloud cover over its primary target, before diverting to Nagasaki.

A similar row of dominoes can be identified leading up to Pearl Harbor and 9/11. Hence the problem with post hoc reasoning and 20/20 hindsight. The branches all lead down to the trunk. But starting at the trunk, there is no telling where a branch will end up. That is what keeps conspiracy theorists in business.

However obvious a chain of cause and effect may be, we have difficulty believing anything we're not predisposed to believe until forced by events to believe it. With good reason—evolution selects against gullibility. Knowing when to stick with the known or embrace the unknown is a core challenge of being human.

Related posts

Kantai Kessen
Twilight of the Zero
Hirohito and the Making of Modern Japan

Labels: deep thoughts, history, japan, politics