The Collapse of Atomic Diplomacy…Again?

The end of the Pacific War historiography of “Atomic Diplomacy” seems destined for a second round of debunking, after the 1980’s declassification of WW2 Ultra files, with what looks like a “Jon Parchell talking to Japanese scholars about Commander Mitsuo Fuchida’s version of Midway” moment. [1]

That is, an accepted American Pacific War historiography is about to be ‘up ended’ by Japanese language scholarship little/unknown in English language for years after its appearance. In this particular case, the ‘scholarship’ is a 2011 NHK documentary titled as follows:

 “Atomic bombing – top secret information that was never utilized”

原爆投下 活(い)かされなかった極秘情報

Original link:

Currently accessible link:

Atomic Bomb Pit #2 - B-29 BocksCar Loading Site
Atomic Bomb Pit #2 – B-29 BocksCar’s Loading Site on Tinian.  This was the plane that killed Nagasaki.  Japanese intelligence tracked it, but Japanese military leaders could not bring themselves to stop it.

The NHK documentary answers questions that “Atomic Diplomacy” has never bothered to ask.  Specifically “What did the Imperial Japanese Military & Government know about the American nuclear weapon program, when did it know it, and what did it do about it.”

NHK’s documentary lays out the following:

  1. The Japanese military knew of the Manhattan project in 1943 and started its own nuclear weapons programs (IJA & IJN) as a result.[2]
  2. The Imperial Japanese Military gave up these nuclear programs in June 1945. [3]
  3. The Imperial Japanese Military & Foreign Ministry were informed of the American Atomic test on July 16, 1945 and refused to believe it was a nuclear detonation.
  4. The code breakers of the Imperial Japanese Army had been tracking the combat operations of the 509th Composite Group including both A-bomb drops.[4] The Imperial General Staff was told of the special message to Washington DC for the Hiroshima attack, sat on the information, and warned no one.
  5. The Imperial General Staff repeated this non-communication performance for the 2nd nuclear attack on Nagasaki.

Not having Japanese language skills myself, I had a link to a 2013 English language translations of the documentary sent to me by an acquaintance.

They are located here:

(Special Post for August 15 – Part 1) Japan’s General Staff Office Knew About Hiroshima and Nagasaki Atomic Bombing in Advance and Did Nothing, According to 2011 NHK Documentary



(Special Post for August 15 – Part 2) Japan’s General Staff Office Knew About Hiroshima and Nagasaki Atomic Bombing in Advance and Did Nothing, According to 2011 NHK Documentary



The author of these posts is an English language ex-pat whose blog was focused upon the Fukashima earthquake and nuclear meltdown.

Too the extent I have been able to validate the NHK documentary, it checks out.

Specifically, excluding Hiroshima and Nagasaki, the 509th Composite Group dropped 49 conventional “Pumpkin bombs” on 20, 23, 26 and 29 July and 8 and 14 August 1945 against 14 different targets in mid-sized Japanese cities. [5] These operations gave the IJA codebreaking unit that NHK profiled all the time it needed to take advantage of the indifferent quality of the code clerks of the 20th Air Force.  In particular, the 20th Air Forces use of uncoded header text starting with a “V” to each message identifying B-29’s as to the island in the Marianas they were based upon.

As NHK put it:

 “June 1945. The special intelligence unit noticed something abnormal. They caught mysterious call signs that they had never heard before. Hasegawa says, “They were call signs in V600s. We’d seen 400s, 500s and 700s, and they come from Saipan, Guam, Tinian. But now, V600s. Something was wrong, we thought.”
They were coming from Tinian Island. On the island that had been using call signs in 700s, there was now a new group of B29 bombers using call signs in 600s. What was their purpose? The unit strengthened its monitoring capability to watch closely.
Tinian Island was taken by the US in August 1944. North Field of Tinian Island, which was the base for Japan bombing raids. A special unit arrived there in June 1945 and started using call signs in V600s. It was the 509th Composite Group, which later dropped atomic bombs in Hiroshima and Nagasaki.”

This sort of mistake was the thing that low level intelligence supporting air operations lived by.  Called “Y-Service” in the UK’s Royal Air Force (RAF) and copied by the USAAF with its “Radio Squadron Mobile and the US Navy carrier group flag radio teams.  This low level signals intelligence system was pioneered by the German language skilled female signals officers of the RAF in 1939-41 first in the Battle of Britain and then fingerprinting the deployment of the Luftwaffe’s night fighter force.  The rapid direction finding, listening on open communications and traffic analysis of Luftwaffe unit code headers like those of the 20th Air Force let RAF “WAAF” and Royal Navy “WRN” female auxiliaries build Luftwaffe air order of battle. [6]

The failures of the 20th Air Force had been picked up in “Ultra” code breaking traffic in Washington DC that resulted in a “Visitation” by War Department Military Intelligence in March 1945 to look at the cryptological security of its code clerks and pilots.  Much was found, but the War Department Ultra officers were more involved with control-based intrigue with the Navy against the USAAF’s 7th Air Forces Radio Squadron Mobile than looking at low level vulnerabilities like the Japanese discovered.

So the Japanese Army code breakers had the signals intelligence version of a “ring side seat” for both the Hiroshima and Nagasaki strikes.

The utter failure of the Imperial General staff to act upon intelligence of the Nagasaki strike – which they had both the intelligence to track and the planes to intercept – is a window into the mind set of the Imperial Japanese military for Ketsu-go.

They had to believe there was no second atomic bomb for their decisive battle to happen. So they believed and didn’t act…and Nagasaki died.

This fantasy belief based neo-Samurai fanaticism could only have been broken by a second atomic bomb.

One was not enough.

With the arrival of the English translation of the NHK documentary after the Ultra file declassification’s, believers in “Atomic Diplomacy” appears to now be in the same belief-based situation the Japanese flag ranks were on August 10, 1945.



Sources & Notes:


[1] Jon Parchell is the co-author of “Shattered Sword: The Untold Story of the Battle of Midway” and Mitsuo Fuchida was the senior flight commander of the First Air Fleet of the First Carrier Division who led the attack on Pearl Harbor and ended the war as a captain. After the WW2 he and Masatake Okumiya co-authored the book Midway, the Battle that Doomed Japan, the Japanese Navy’s Story.  (See link:–A-Tale-of-Three-Whopper)


[2] The Imperial Japanese Military’ s atomic bomb or “Genzai Bakuden” program had a two separate Army and Navy projects;  the Army’s Ni-Go program and the Navy’s F-Go.  Neither of these programs produced a working device, despite 1946 rumors about a test near Hungnam, Korea that were later incorporated into the 1985 book “Japan’s Secret War: Japan’s Race Against Time to Build Its Own Atomic Bomb.”

The pages 720-21 of the closing chapter of John Prados’ 1995  “COMBINED FLEET DECODED: The Secret History of American Intelligence and the Japanese Navy in World War II” mentions the IJN F-Go nuclear program.

See also:

Mr. Robert Pfeffer, Physical Scientist, U.S. Army Nuclear and CWMD Agency, “Japan Had an Atomic Bomb (Genzai Bakuden) Program in WWII?”, Combating WMD Journal Issue 7, [Spring/Summer 2011] pages 16 – 19


Japanese Atomic Bomb Project, Wednesday, May 25, 2016


[3] The primary reasons being wishful thinking about American nuclear capabilities, B-29 damage to urban areas removing the industrial means and the higher priority of implementing Ketsu-Go defense plan for Kyushu.  “Ketsu-Go” was a series of strategy options outlined in an 8 April 1945 Imperial Japanese Military Directive. It stated that the Imperial Military would endeavor to crush the Americans while the invasion force was still at sea with suicide or “Tokko” forces.

See: Dr. K. Jack Bauer’s and Dr. Alan C. Coox’s “OLYMPIC VS KETSU-GO” Marine Corps Gazette, August 1965, Vol. 49, No. 8., reprinted at the Hyperwar site here:

See also FAS link:



[4] It is not surprising that the Imperial Japanese Army was so successful at tracking the 509th Composite Group.  The horrid signals insecurity of the USAAF in general and 20th Air Force in particular has been a consistent theme in secret US government cryptographic histories both at the time and immediately after WW2.




The USAAF suffered from a much smaller base of officers compared to its eventual size compared to the rest of the War Department and this consistently showed up in its code clerks indifferent-to-poor habits in the use of the M-209 Hagelan encoding machine.  The M-209 was a US Army medium-level cryptographic system equivalent to the German Enigma.  It was used at Division levels and below in the ground forces and theoretically at Wing and below in the Army Air Forces.  The M-209 could and should have had a daily change of machine setting to prevent systematic break-ins over long periods.  The only theater where this seems to have happened consistently was in General Douglas MacArthur’s SWPA as both Army divisions in England, and USAAF units world wide, had their M-209 messages broken consistently by German and Japanese code breaking units.


Setsuo Fukutomi, “Mathematics and War in Japan.” pgs 153-159 in Mathematics and War, © 2003,  Editors: Booß-Bavnbek, Bernhelm, Høyrup, Jens (Eds.) Birkhauser, ISBN:978-3-7643-1634-1

KOTANI Ken, “Japanese Intelligence in WWII: Successes and Failures,” NIDS Security Reports pages 2 – 27

Japanese Intelligence Successes in World War II

Hans Johnson

Jan 25, 2012


Christos Military and Intelligence Corner blog posts:

Japanese codebreakers of WWII

Friday, July 27, 2012

The American M-209 cipher machine

Friday, June 1, 2012


[5] The “Pumpkin Bomb” was the shell of a “Fat Man” plutonium bomb filled with over 5,000-lbs of conventional explosive.  It’s operational use and combat effects were well documented, if somewhat ignored by succeeding generations of historians compared to the two nuclear strikes on Japan.


See also:



Physical Damage Division

Dates of Survey: 20 October-16 November 1945

Date of Publication: May 1947


As well as:

History of 509th Composite Group

313th Bombardment Wing

Twentieth Air Force

Activation to 15 August 1945


[6] Aileen Clayton’s memoir “The Enemy is Listening” is the bible of the creation of the “Y-Service” and is a “must read” for understanding intelligence support to air forces in WW2.  It is also important in helping to frame the bureaucratic intelligence wars between the senior political/flag rank “Ultra” level code breaking, which was all about centralization and control, versus the need for immediate & actionable intelligence for the soldier/sailor/airman/marine.

For more modern “Y-Service” class intelligence scholarship see the following:

Dr Diane Putney, “USAAF Intelligence and the European War – Daylight Strategic Air War in Europe,”  found in

Captain Gilles K. Van Nederveen, USAF, “Wizardry for Air Campaigns Signals Intelligence Support to the Cockpit,” Research Paper 2001-03, August 2001, College of Aerospace Doctrine,, Research and Education, Air University, Maxwell AFB AL 36112-6428

John Stubbington, “Kept in the Dark – The Denial to Bomber Command of Vital Ultra and Other Intelligence During World War II,” Pen & Sword, 2010 432 pages, b/w illustrations, hardcover, Electronic Edition Aug 13, 2013, Amazon Digital Services, : B007ZD13CY, ISBN-13: 978-1848841833


[7] The issue of US Military centralization and control of low level signal intelligence units like the USAAF’s 7th RSM for “detailed analysis” versus the USAAF’s demand for distributed and immediate exploitation, plus the intrigues there in, are detailed in the following declassified Ultra documents:



SRH- 200 – OP-20-G FILE ON ARMY-NAVY COLLABORATION 1931-1945 PART 2 (1 JUNE 1944 – 22 AUGUST 1945)

11 thoughts on “The Collapse of Atomic Diplomacy…Again?”

  1. Thanks for the info. But is this really surprising? The potential for nuclear bombs was well known in the scientific community before WWII — which is why both Germany and Japan had their own nuclear programs. It is tough to keep secrets from the enemy — remember that VP Truman knew nothing about the development & testing of US nuclear weapons, while Stalin was getting up-to-the-minute reports. The US had been fire bombing most Japanese cities of any size for months — and the Japanese had been able to do almost nothing to stop those attacks, since their air force was so badly depleted.

    Only Hiroshima and Nagaski and a couple of other cities had been left untouched. Without breaking any codes, some of the Japanese staff must have wondered what special hell awaited those places. Isn’t it more likely that the Japanese Imperial Staff did nothing about the information on the attack on Nagasaki because in reality there was nothing they could have done?

    By the way, let me put in a plug for the movie “Midway”, which also features the important role played by code-breakers. Excellent movie! Although it left this viewer with a sad realization about how far we in the West have fallen in terms of attitudes & confidence.

  2. I don’t recall where or how, but I read about this earlier in the week at some other site.

    They had to believe there was no second atomic bomb for their decisive battle to happen. So they believed and didn’t act…and Nagasaki died.This fantasy belief based neo-Samurai fanaticism could only have been broken by a second atomic bomb.One was not enough.

    Yet we still hear some “peace-lovers” saying that the US should have invited the Japanese to a demonstration atomic bomb explosion somewhere.

  3. Gavin made exactly the points that I was about to make only more literately.

    The B-29s and their fighter escorts dominated the skies over Japan and there was very little the Japanese HQ could do to save any city from bombing.

  4. A supporting fact is that General Curtis LeMay ordered the defensive guns stripped from the B-29s early in the bombing campaign. The lack of Japanese fighter opposition and the American covering fighters meant that the gun-less B-29s could deliver a heavier bomb load to target.

    The American fighters usually split off and went into ground attack mode over Japan.

  5. From the site linked by Mike K: “B-29s carried out around 33,000 sorties [against Japan] with a loss rate of 1.38% …”

    That is astonishingly low. Also, that is an average over the entire war, and it is fairly clear that Japan’s ability to inflict losses declined substantially as the war went on and Japan’s industrial capacity and fuel supplies were diminished.

    Back to the obvious conclusion — there was very little that Japan’s military could have done against the nuclear attacks. From other books on those two attacks, it seems that weather was more of an issue for those bombers than Japanese opposition.

  6. I have read, don’t remember where but maybe “Downfall” by Richard Frank, that the reason the Japanese thought there couldn’t be a second bomb was they sent a physicist team to Hiroshima to collect and analyze samples, and determined it was a U-235 bomb. From their own A-bomb program, the Japanese had a good sense of how hard it was to separate enough U-235 isotope to make a bomb, so they thought it impossible that the US could have two. (NOT blind loyalty to Ketsu-Go, but very rational.)

    Of course, that was Little Boy. Fat Man at Nagasaki was a Pu-239 implosion bomb and the reactor at Hanford was turning out enough Pu-239 to make 2 or 3 bombs a month. And as soon as the Japanese determined that the Nagasaki bomb was Pu-239 and their physicists described how Pu-239 could be made in quantity, and if the US could produce one it had the capacity–a reactor–to produce many more; and they gave up. What surprised them was that the US had made a bomb out of plutonium–which really was a technological tour de force for 1945. The Japanese scientists knew all the basic science of how to make Pu-239, but turning it into a bomb was hugely more complicated than a simple U-235 “gun,” which we never tested because we were so sure it would work.

    So, yeah, for reasons the US didn’t understand at the time, the Hiroshima (uranium) bomb was NOT enough, it needed a plutonium bomb to get the message across. And if you ignore what people actually knew at the time, you could argue that the Hiroshima bomb was the unnecessary one because it used the “wrong” fissionable material to intimidate them into surrender. One bomb might have been enough, if it was Pu-239 based.

  7. Mhj,

    Japanese science had no idea that Plutonium existed until August 9, 1945.

    It’s discovery at Nagasaki is what killed Ketsu-Go.

    Logically, Plutonium (PU) had to be a by-product of uranium enrichment and easier to separate chemically than U-235 from U-238.

    That is, PU atomic bombs had to be some larger than one multiple of U-235 atomic bombs.

    Thus America had the option of “Nuking Japan from orbit” (30K feet might as well have been orbit for Japanese fighter planes) instead of invading.

    That was “Ketsu-Gone” as far as the Imperial Japanese Military leadership was concerned.

  8. Plutonium was discovered by Fermi in 1934 in Rome, so it’s pretty certain that the Japanese knew about it. Whether they could have detected it quickly enough to enter into the calculations of the government is something else. It would have been mixed in with a lot of other fission products, some with very short half lives that would have been challenging given the techniques of the time. They may have been able to tell that two completely different bombs had been used.

  9. MCS, Fermi’s “hesperium” was a mixture of barium, krypton, and other elements.

    Plutonium-238 and PU-239 were isolated as elements in 1940 and 1941 respectively.

    Text via wikipedia article link:

    “Plutonium (specifically, plutonium-238) was first produced and isolated on December 14, 1940, and chemically identified on February 23, 1941, by Glenn T. Seaborg, Edwin McMillan, Joseph W. Kennedy, and Arthur Wahl by deuteron bombardment of uranium in the 60-inch (150 cm) cyclotron at the Berkeley Radiation Laboratory at the University of California, Berkeley.[57][58] In the 1940 experiment, neptunium-238 was created directly by the bombardment but decayed by beta emission with a half-life of a little over two days, which indicated the formation of element 94.[31]

    A paper documenting the discovery was prepared by the team and sent to the journal Physical Review in March 1941,[31] but publication was delayed until a year after the end of World War II due to security concerns.[59] At the Cavendish Laboratory in Cambridge, Egon Bretscher and Norman Feather realized that a slow neutron reactor fuelled with uranium would theoretically produce substantial amounts of plutonium-239 as a by-product. They calculated that element 94 would be fissile, and had the added advantage of being chemically different from uranium, and could easily be separated from it.[21]

    McMillan had recently named the first transuranic element neptunium after the planet Neptune, and suggested that element 94, being the next element in the series, be named for what was then considered the next planet, Pluto.[4][note 2] Nicholas Kemmer of the Cambridge team independently proposed the same name, based on the same reasoning as the Berkeley team.[21] Seaborg originally considered the name “plutium”, but later thought that it did not sound as good as “plutonium”.[61] He chose the letters “Pu” as a joke, in reference to the interjection “P U” to indicate an especially disgusting smell, which passed without notice into the periodic table.[note 3] Alternative names considered by Seaborg and others were “ultimium” or “extremium” because of the erroneous belief that they had found the last possible element on the periodic table.[63]”

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