Secrecy, verification, and purposeful ignorance

The history of nuclear secrecy is an interesting topic for a lot of reasons, but one of the more wonky ones is that it is an inversion of the typical studies that traditionally are done in the history of science. The history of science is usually a study of how knowledge is made and then circulates; a history of secrecy is about how knowledge is made and then is not circulated. Or, at least, its non-circulation is attempted, to various degrees of success. These kinds of studies are still not the “norm” amongst historians of science, but in recent years have become more common, both because historians have come to understand that secrecy is often used by scientists for various “legitimate” reasons (i.e., preserving priority), and because historians have come to understand that the study of deliberately-created ignorance has been a major theme as well (e.g., Robert Proctor has coined the term agnotology to describe the deliberate actions of the tobacco industry to foster ignorance and uncertainty regarding the link between lung cancer and cigarettes).

The USS Nautilus with a nice blob of redaction. No reactor core for you!

The USS Nautilus with a nice blob of redaction. No reactor for you! From a 1951 hearing of the Joint Committee on Atomic Energy — apparently the reactor design is still secret even today?

What I find particularly interesting about secrecy, as a scholar, is that it is like a sap or a glue that starts to stick to everything once you introduce a little bit of it. Try to add a little secrecy to your system and pretty soon more secrecy is necessary — it spreads. I’ve remarked on this some time back, in the context of Los Alamos designating all spheres as a priori classified: once you start down the rabbit-hole, it becomes easier and easier for the secrecy system to become more entrenched, even if your intentions are completely pure (and, of course, more so if they are not).

In this vein, I’ve for awhile been struck by the work of some friends of mine in the area of arms control work known as “zero-knowledge proofs” (and the name alone is an attention-grabber). A zero-knowledge proof is a concept derived from cryptography (e.g., one computer proves to another that it knows a secret, but doesn’t give the secret away in the process), but as applied to nuclear weapons, it is roughly as follows: Imagine a hypothetical future where the United States and Russia have agreed to have very low numbers of nuclear warheads, say in the hundreds rather than the current thousands. They want mutually verify each other’s stockpiles are as they say they are. So they send over an inspector to count each other’s warheads.

Already this involves some hypotheticals, but the real wrench is this: the US doesn’t want to give its nuclear design secrets away to the Russian inspectors. And the Russians don’t want to give theirs to the US inspectors. So how can they verify that what they are looking at are actually warheads, and not, say, steel cans made to look like warheads, if you can’t take them apart?

Let's imagine you had a long line of purported warheads, like the W80, shown here. How can you prove there's an actual nuke in each can, without knowing or learning what's in the can? The remarkable W80s-in-a-bunker image is from a blog post by Hans Kristensen at Federation of American Scientists.

Let’s imagine you had a long line of purported warheads, like the W80, shown here. How can you prove there’s an actual nuke in each can, without knowing or learning what’s in the can? The remarkable W80s-in-a-bunker image is from a blog post by Hans Kristensen at Federation of American Scientists.

Now you might ask why people would fake having warheads (because that would make their total number of warheads seem higher than it was, not lower), and the answer is usually about verifying warheads put into a queue for dismantlement. So your inspector would show up to a site and see a bunch of barrels and would be told, “all of these are nuclear warheads we are getting rid of.” So if those are not actually warheads then you are being fooled about how many nukes they still have.

You might know how much a nuclear weapon ought to weigh, so you could weigh the cans. You might do some radiation readings to figure out if they are giving off more or less what you expect a warhead might be giving you. But remember that yours inspector doesn’t actually know the configuration inside the can: they aren’t allowed to know how much plutonium or uranium is in the device, or what shapes it is in, or what configuration it is in. So this will put limitations both on what you’re allowed to know beforehand, and what you’re allowed to measure.

Now, amusingly, I had written all of the above a few weeks ago, with a plan to publish this issue as its own blog post, when one of the groups came out with a new paper and I was asked whether I would write about it for The New Yorker‘s science/tech blog, Elements. So you can go read the final result, to learn about some of the people (Alexander Glaser, Sébastien Philippe, and R. Scott Kemp) who are doing work on this: “The Virtues of Nuclear Ignorance.” It was a fun article to write, in part because I have known two of the people for several years (Glaser and Kemp) and they are curious, intelligent people doing really unusual work at the intersection of technology and policy.

Virtues of Nuclear Ignorance

I won’t re-describe their various methods of doing it here; read the article. If you want to read their original papers (I have simplified their protocols a bit in my description), you can read them here: the original Princeton group paper (2014), the MIT paper from earlier this year (2016), and the most recent paper from the Princeton group with Philippe’s experiment (2016).

In the article, I use a pine tree analogy to explain the zero-knowledge proof. Kemp provided that. There are other “primers” on zero-knowledge proofs on the web, but most of them are, like many cryptographic proofs, not exactly intuitive, everyday scenarios. One of the ones I considered using in the article was a famous one regarding a game of Where’s Waldo:

Imagine that you and I are looking at a page in one book of Where’s Waldo. After several minutes, you become frustrated and declare that Waldo can’t possibly be on the page. “Oh, but he is,” I respond. “I can prove it to you, but I don’t want to take away the fun of you finding him for yourself.” So I get a large piece of paper and cut out a tiny hole in exactly the shape of Waldo. While you are looking away, I position it so that it obscures the page but reveals the striped wanderer through the hole. That is the essence of a zero-knowledge proof — I prove I’m not bluffing without revealing anything new to you.

I found Waldo on the map of Troy. How can I prove it without giving his location away? A digital version of the described "proof": I found his little head and cut it out with Photoshop. But how do you know that's his head from this image? (Waldo from Where's Waldo)

I found Waldo in the Battle of Troy. How can I prove it without giving his location away? A digital version of the described “proof”: I found his little head and cut it out with Photoshop. In principle, you now know I really found him, without knowing where he is… but might that face be from a different Waldo page? (Image from Where’s Waldo)

But a true zero-knowledge proof, though, would also avoid the possibility of faking a positive result, which the Waldo example fails: I might not know where Waldo is on the page we are mutually looking at, but while you are not looking, I could set up the Waldo-mask on another page where I do know he is hiding. Worse yet, I could carry with me a tiny Waldo printed on a tiny piece of paper, just for this purpose. This might sound silly, but if there were stakes attached to my identification of Waldo, cheating would become expected. In the cryptologic jargon, any actual proof need to be both “complete” (proving positive knowledge) and “sound” (indicating false knowledge). Waldo doesn’t satisfy both.

Nuclear weapons issues have been particularly fraught by verification problems. The first attempt to reign in nuclear proliferation, the United States’ Baruch Plan of 1946, failed in the United Nations in part because it was clear that any meaningful plan to prevent the Soviet Union from developing nuclear weapons would involve a freedom of movement and inspection that was fundamentally incompatible with Stalinist society. The Soviet counter-proposal, the Gromyko Plan, was essentially a verification-free system, not much more than a pledge not to build nukes, and was subsequently rejected by the United States.

The Nuclear Non-Proliferation Treaty has binding force, in part, because of the inspection systems set up by the International Atomic Energy Agency, who physically monitor civilian nuclear facilities in signatory nations to make sure that sensitive materials are not being illegally diverted to military use. Even this regime has been controversial: much of the issues regarding Iran revolve around the limits of inspection, as the Iranians argue that many of the facilities the IAEA would like to inspect are militarily secret, though non-nuclear, and thus off-limits.

From the Nature Communications paper — showing (at top) the principle of what a 2D example would look like (with Glaser's faux Space Invader) — the complement is the "preload" setting mentioned in my New Yorker article, so that when combined with the new reading, ought to result in a virtually null reading. At bottom, the setup of the proof-of-concept version, with seven detectors.

From the Nature Communications paper — showing (at top) the principle of what a 2D example would look like (with Glaser’s faux Space Invader) — the complement is the “preload” setting mentioned in my New Yorker article, so that when combined with the new reading, ought to result in a virtually null reading. At bottom, the setup of the proof-of-concept version, with seven detectors.

One historical example about the importance of verification comes from the Biological Weapons Convention in 1972. It contained no verification measures at all: the USA and USSR just pledged not to develop biological weapons (and the Soviets denied having a program at all, a flat-out lie). The United States had already unilaterally destroyed its offensive weapons prior to signing the treaty, though the Soviets long expressed doubt that all possible facilities had been removed. The US lack of interest in verification was partially because it suspected that the Soviets would object to any measures to monitor their work within their territory, but also because US intelligence agencies didn’t really fear a Soviet biological attack.

Privately, President Nixon referred to the BWC as a “jackass treaty… that doesn’t mean anything.” And as he put it to an aide: “If somebody uses germs on us, we’ll nuke ‘em.”1

But immediately after signing the treaty, the Soviet Union launched a massive expansion of their secret biological weapon work. Over the years, they applied the newest genetic-engineering techniques to the effort of making whole new varieties of pathogens. Years later, after all of this had come to light and the Cold War had ended, researchers asked the former Soviet biologists why the USSR had violated the treaty. Some had indicated that they had gotten indications from intelligence officers that the US was probably doing the same thing, since if they weren’t, what was the point of a treaty without verification?

A bad verification regime, however, can also produce false positives, which can be just as dangerous. Consider Iraq, where the United States set up a context in which it was very hard for the Iraqi government to prove that it was not developing weapons of mass destruction. It was easy to imagine ways in which they might be cheating, and this, among other factors, drove the push for the disastrous Iraq War.

In between these extremes is the more political considerations: the possibility of cheating at treaties invites criticism and strife. It gives ammunition to those who would oppose treaties and diplomacy in general. Questions about verification have plagued American political discourse about the US-Iranian nuclear deal, including the false notion that Iran would be allowed to inspect itself. If one could eliminate any technical bases for objections, it has been argued, then at least those who opposed such things on principle would not be able to find refuge in them.

The setup from Kemp, et al. The TAI is the Treaty Accountable Item, i.e. the warhead you are testing.

The setup from Kemp, et al. The TAI is the Treaty Accountable Item, i.e. the warhead you are testing.

This is where the zero-knowledge protocols could come in. What’s interesting to me, as someone who studies secrecy, is if the problem of weapon design secrecy were removed, then this whole system would be unnecessary. It is, on some level, a contortion: an elaborate work-around to avoid sharing, or learning, any classified information. Do American scientists really think the Russians have any warhead secrets that we don’t know, or vice versa? It’s possible. A stronger argument for continued secrecy is that there are ways that an enemy’s weapons could be rendered ineffective if their exact compositions were known (neutrons, in the right quantity, can “kill” a warhead, causing its plutonium to heat and expand, and causing its chemical high-explosives to degrade; if you knew exactly what level of neutrons would kill a nuke, it would play into strategies of trying to defend against a nuclear attack).

And, of course, that hypothetical future would include actors other than the United States and Russia: the other nuclear powers of the world are less likely to want to share nuclear warhead schematics with each other, and an ideal system could be used by non-nuclear states involved in inspections as well. But even if everyone did share their secrets, such verification systems might still be useful, because they would eliminate the need for trust altogether, and trust is never perfect.

A little postscript on the article: I want to make sure to thank Alex Glaser, Sébastien Philippe, and R. Scott Kemp for devoting a lot of their weekends to making sure I actually understood the underlying science of their work to write about it. Milton Leitenberg gave me a lot of valuable feedback on the Biological Weapons Convention, and even though none of that made it into the final article, it was extremely useful. Areg Danagoulian, a colleague of Kemp’s at MIT who has been working on their system (and who first proposed using nuclear resonance fluorescence as a means of approaching this question), didn’t make it into the article, but anyone seriously interested in these protocols should check out his work as well. And of course the editor I work with at New Yorker, Anthony Lydgate, should really get more credit than he does for these articles, and on this one in particular managed to take the unwieldy 5,000 word draft I sent him and chop it down to 2,000 words very elegantly. And, lastly, something amusing — I noticed that Princeton Plasma Physics Laboratory released a film of Sébastien talking about the experiment. Next to him is something heavily pixellated out… what could it be? It looks an awful lot like a copy of Unmaking the Bomb, a book created by Glaser and other Princeton faculty (and I made the cover), next to him…

  1. On the “jackass treaty,” see Milton Leitenberg and Raymon Zilinskas, The Soviet Biological Weapons Program: A History (Harvard University Press, 2012), quoted on 537.  On “we’ll nuke ’em,” the aide was William Safire. For his account, see William Safire, “Iraq’s Tons of Germs,” New York Times (13 April 1995).

Operation Crossroads at 70

This summer is the 70th anniversary of Operation Crossroads, the first postwar nuclear test series. Crossroads is so strange and unusual. 1946 in general ought to get more credit as an interesting year, as I’ve written about before. It was a year in flux, where a great number of possible futures seemed possible, before the apparently iron-clad dynamics of the Cold War fell into place. Crossroads happens right in the middle of the year, and arguably made a pretty big contribution to the direction that we ended up going. Such is the subject of my latest article for the New Yorker‘s Elements blog, “America at the Atomic Crossroads.” Today is the anniversary of the Baker shot, which Glenn Seaborg dubbed “the world’s first nuclear disaster.”

America at the Atomic Crossroads

There are a lot of things that make Crossroads interesting to me. The bomb was still in the hands of the Manhattan Project. The Atomic Energy Act of 1946 had not yet been signed into law (Truman would sign it in August, and it would go into effect in January 1947), so the Atomic Energy Commission did not yet exist.

There were these amazing interservice rivalry aspects: the whole backdrop is a Navy vs. Army tension. The Manhattan Project, and the Army Air Forces, had gotten all the glory for the bomb. The Navy didn’t want to be left out, or seen as irrelevant. Hence them hosting a big test, and glorying in the fact that a Nagasaki-sized atomic bomb doesn’t completely destroy a full naval squadron. (Which was no surprise to anybody on the scientific or military side of things.)

The US had only about 10 atomic bombs at the time. So they expended about 20% of their entire nuclear arsenal on these tests, for relatively little military knowledge gained. The Los Alamos scientists were pretty lukewarm on the whole operation — it just didn’t seem like it was getting them much. One wonders, if the bomb had not still be under military control, whether it would have happened.

Photograph of the early mushroom cloud by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

Photograph of the early mushroom cloud of Crossroads Able by LIFE photographer Frank Scherschel, with a darkened filter to compensate for the brightness of the flash. Source.

The first shot, Able, was something of a flub. The fact that it missed its target meant that for public relations purposes it was seen as very ineffective, but it also means that their scientific observations were largely pretty useless. In fact, it missed its target and blew up over one of the main instrumentation ships.

If you read most sources about Crossroads they will say that the source of the Able miss was undetermined, but if you dig down a little deeper you find some pretty plausible solutions (and the reason why the official verdict was “undetermined”). Paul Tibbets, the captain of the Enola Gay and overall head of the atomic delivery group, was pretty clear that it was human error. He said that even before the shot they realized that the crew of the B-29 which dropped it, Dave’s Dream, had gotten bad information about the weather conditions, but that they ignored attempts at correction. Tibbets would re-run (with a dummy bomb) the drop with the correct information (and got very close to the target), and also re-ran it with the wrong information (which missed by nearly the same amount as the Able shot). But the USAAF really didn’t want to throw their bombardier and plane crew under the bus. So they hinted it might be a problem with the ballistics of the weapon (which were indeed a bit tricky), which infuriated the Manhattan Project officials. Anyway, everyone seems to have been satisfied by just saying they couldn’t figure out where the error was. But Tibbets’ account seems most plausible to me.1

Crossroads was not secret operation, though there was much classified about it. There were full-spread articles about its purpose in national news publications both before and after its tests. There was probably no test series so publicly conducted by any nuclear power — announced well in advance, covered by the press in real-time, and then heavily publicized afterwards. The fact that the Soviets were invited to a US nuclear test operation (something that would not happen again until the late-1980s) opens up whole other dimensions.

Mikhail Meshcheryakov ("Mike"?) in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

Mikhail Meshcheryakov  in 1946. At right he is on the USS Panamint, at the Crossroads test. Source: Mikhail Grigorivich Meshcheryakov, on the 100th-anniversary of his birth (Dubna, 2010).

The Soviets had three observers at the test: Professor Semyon P. Aleksandrov, a geologist who had worked on the prospecting of uranium; Mikhail G. Meshcheryakov, an experimental physicist; and Captain Abram M. Khokhlov, who attended as a member of the international press corps (he wrote for the Soviet periodical Red Fleet). I found a really amusing little anecdote about the Soviet observers from one of the men who worked the Manhattan Project security detail on Crossroads: Aleksandrov was someone they knew already (he was a “dear old geologist”), but Meshcheryakov was someone “whose name was known, but no one had met personally leading some of us to support he was really an NKVD agent watching Aleksandrov.”

I found nothing in the Russian source materials (mentioned below) that would indicate that Meshcheryakov was NKVD, though he was definitely the one who wrote up the big report on Crossroads that was given to Beria, who summarized it for Stalin. Meshcheryakov’s report is not among the declassified documents released by the Russians, so who knows if it has any political commentary on Aleksandrov in it. Meshcheryakov ended up having a rather long and distinguished physics career in the USSR, though there is almost no English-language discussion of him on the Internet. Aleksandrov, the “dear old geologist,” was actually a major Soviet big-wig in charge of mining operations, which at that time meant he was high in the Gulag system, which was run by the NKVD. For what it’s worth.2

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

Radiation from the Crossroads Baker shot — the radiation went up with the cloud, and then collapsed right back down again with it, resulting in a very limited extent of radiation (the entire chart represents only 4.5 miles on each axis), but very high intensities. Chart source: DNA 1251-2-EX. Collapsed cloud picture source: Library of Congress.

It was also something of the real birth of “atomic kitsch.” There are some examples from before Crossroads, but there is just a real flourishing afterwards. It seems to have taken a year or so after Hiroshima and Nagasaki for enough time to have passed for Americans to start to regard nuclear weapons entirely frivolously. With Crossroads in particular, a deep connection between sex and death (Freud’s favorites) circled around the bomb. This is where we start to see the sorts of activities that would later result in the “Miss Atomic Bomb” contests, the release of the really kitchy songs, and, of course, the Bikini swimsuit, named after the “atomic bomb island,” as LIFE put it.

The key fulcrum of my article is a meditation on the “crossroads” metaphor, and I should probably note that it was, to some degree, intentional. Vice Admiral William Blandy was reported by the New York Times to have told Congress, that the name was chosen for its “possible significance,” which the Times writer interpreted to mean “that seapower, airpower, and perhaps humanity itself — were at the crossroads.”3

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

An unusual color (but not colorized!) photograph of the Crossroads Baker detonation, from LIFE magazine. Source.

What’s interesting to me is that Blandy clearly saw some aspects of the “crossroads,” but there was much he couldn’t have seen — the atomic culture, the arms race, the contamination, the nuclear fears. He knew that “crossroads” was a good name for what they were doing, but it was an even better name than he could have known, for both better and worst.

As before, I wanted to take a moment to give some credit/citation information that wasn’t workable into the New Yorker blog post (where space, and thus academic nicety, is constrained).

The best overall source on Crossroads, which I found invaluable, is Jonathan Weisgall’s Operation Crossroads: The Atomic Tests at Bikini Atoll (Naval Institute Press, 1994). Weisgall has been a legal counsel on behalf of the Marshallese, and his book is just a wealth of information. I was pleased to find a few things that he didn’t have in his book, because it’s a really tough challenge given how much work he put into it. If you find Crossroads interesting, you have to read Weisgall.

Rita Hayworth on the Crossroads Able bomb, "Gilda." Photo by Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Rita Hayworth on the Crossroads Able bomb, “Gilda.” Photo courtesy Los Alamos National Laboratory, via Peter Kuran and Bill Geerhart.

Bill Geerhart, who writes the excellent blog CONELRAD Adjacent (and is the one behind the Atomic Platters series of Cold War songs), has done some really wonderful work on the cultural aspects of Crossroads over the years. His posts on the mushroom cloud cake, and his sleuthing regarding the Rita Hayworth connection, are amazing and worth reading in their entirety. Peter Kuran, the visual effects wizard who made the documentary Trinity and Beyond, among other films and works, was very helpful in providing recently-declassified imagery of the Crossroads bombs, including photos (which I first saw on Geerhart’s blog) of the Rita Hayworth image on the side of the bomb themselves. (I will be writing more about Kuran and his work in the near future…)

Holly Barker’s Bravo for the Marshallese (Thomson/Wadsworth, 2004), is immensely useful as an anthropologist’s view of the Marshallese people and their experiences after the test. My invocation of the Marshallese language for birth defects comes directly from Barker’s book, pages 81 and 106-107. It is a powerful, disturbing section of the book.

Selection from Life magazine's coverage of Crossroads — two visions of the animal testing. Source.

Selection from Life magazine’s coverage of Crossroads — two visions of the animal testing. Source.

Most of the information I got about the Soviet view of Crossroads comes from the multi-volume Atomniy Proekt SSSR document series released by the Russian Federation. I had the full set of these before it was cool, but now Rosatom has put them all online. Scholars have been picking over these for awhile (I have written on them once before), I haven’t seen anybody use the particular documents relating to Crossroads before, but you in Tom (Volume) 2, Kniga (Book) 6, the documents I found most useful were 44 (pp. 130-132), 48 (135-136), 50 (137), 76 (184-188), and 106 (246-248). They show the picking of the delegation of observers, brief biographies of the observers, a summary of Meshcheryakov’s report (his full 110-page report on Crossroads is not included), and some later aspects of Meshcheryakov’s involvement with the planning of the first Soviet nuclear test in 1949 (in which his Bikini experience was offered up as his bonafides).

The other really unusual little source I used for my article is the letter from Percy Bridgman. The letter was sent from Bridgman to Hans Bethe, who relayed it to Norris Bradbury at Los Alamos, who sent it to General Groves. You can read it here. I have been sitting on it for a long time — I almost wrote a blog post about it in 2012, but decided not to for whatever reason. When I worked at the American Institute of Physics I had an opportunity to poke around Bridgman’s life and writings a bit, and he’s really an interesting character. He was the one at Harvard who served as J. Robert Oppenheimer’s physics advisor, and his own work on high-pressure physics not only won him the Nobel Prize of 1946 (which is a nice coincidence for the Crossroads article), but also was used (and is still classified, as far as I can tell) on the Manhattan Project (they seem to have sent him plutonium samples, so you can imagine the kind of work he was doing and why it might still be classified — almost everything on plutonium under high pressures is classified in the United States).

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics

Percy W. Bridgman (L) talking with Harvard colleague (and future Trinity test director) Kenneth Bainbridge on a Massachusetts beach, 1934. Source: Emilio Segrè Visual Archives, American Institute of Physics.

Bridgman gave a number of talks associated with his Nobel Prize that really tried to get at the heart of what the effects of World War II would be for physics as a discipline. He was very much afraid that Big Science (which hadn’t yet been given that name) would really destroy work like his own, which he saw as small-scale, individual, and not focused on particular applications. He was also very interested in topics related to the philosophy of science, something that a lot of modern-day practicing physicists openly disdain. His Wikipedia page gives a nice, brief overview of his life, and even touches on the poignant circumstances of his death.4.

  1. This is discussed at length in Jonathan Weisgall’s Operation Crossroads, pp. 201-204.
  2. The account of the security officer is Charles I. Campbell, A Questing Life: The Search for Meaning (New York: iUniverse, 2006). This appears to be a self-published memoir, the sort of thing one would never run across without Google Books. On Aleksandrov’s Gulag connections (which seem plausible given his uranium connections), see this page on his Hero of Socialist Labor award. One of the few English-language articles on Meshcheryakov is available here.
  3. Sidney Shallet, “Test Atomic Bombs to Blast 100 Ships at Marshall Atoll,” New York Times (25 January 1946), 1. Blandy’s full quote on the name from the testimony: “The schedule of target dates for this operation, which will be known by the code word ‘CROSSROADS’—and I would like to explain that we have chosen that merely for brevity in dispatches and other communications, and we chose it with an eye to its possible significance—now calls for the first test to be accomplished early in May, over target ships at an altitude of several hundred feed.” A lot of the sources about Crossroads include Shallet’s bit about “perhaps humanity itself” as a quote of Blandy’s, but it’s not in the transcript that I can see. Hearing before the Special Committee on Atomic Energy, United States Senate, Pursuant to S. Res. 179, Part 4, 79th Congress, 2nd Session (24 January 1946), on 457.
  4. The citation for the Bridgman letter is: Percy W. Bridgman to Hans Bethe, forwarded by Norris Bradbury to Leslie Groves via TWX (13 March 1946), copy in the Nuclear Testing Archive, Las Vegas, NV, document NV0128609.

Mapping the US nuclear war plan for 1956

A few months back, the National Security Archive made national headlines when they released a 1956 US target list they had obtained under the Freedom of Information Act. The target list outlined over a thousand Strategic Air Command nuclear targets in the Soviet Union, Eastern Bloc, the People’s Republic of China, and North Korea. The Archive had posted a small graphic of the ones in Eastern Europe, but hadn’t digitized the full list. Several weeks ago, the people at the Future of Life Institute did just this, digitizing the complete dataset — no small task, given that these were spread over several hundred, non-OCR-able pages of smudgy, 60-year-old government documents.1

A sampling of the 1956 target list obtained by the National Security Archive. The digits encode latitude and longitude points, among other bits of information.

A sampling of the 1956 target list obtained by the National Security Archive. The digits encode latitude and longitude points, among other bits of information.

I recently attended a conference that the FLI put on regarding nuclear war. FLI was co-founded by the MIT physicist Max Tegmark and his wife Meia (among a few others), both of whom I was glad I got to spend some time with, as they are interesting, intelligent people with interesting histories. They are interested in promoting work that decreases existential threats to the human race, which they see as possibly including things like nuclear war and nuclear winter, but also unhampered artificial intelligence, climate change, and the possible negative futures of biotechnology. These are all, of course, controversial topics (not always controversial among the same groups of people, to be sure). They’re an interesting group, and they are stirring up some interesting discussions, which I think is an unambiguously positive thing even if you don’t agree that all of these things are equally realistic threats, or threats on the same level.2

The FLI's digitized version of the target list. Click the image to view their interactive version.

The FLI’s digitized version of the target list. Click the image to view their interactive version.

The target list, mapped out as the FLI did above, is already pretty impressive. While I was at the conference, I got the idea that it wouldn’t be that hard to reconfigure a few parts of the NUKEMAP code to allow me to import huge numbers of target lists in the right format. NUKEMAP already supports the targeting of multiple nukes (the feature is a little cryptic — you create a detonation, then click “launch multiple,” then move the cursor and can then create another one, and repeat as necessary), but it didn’t have any automatic way of importing a large number of settings. Once I had done that, I then thought, what would it look like if I used realistic weather data to determine the fallout patterns from surface bursts? It only took a little bit of further work to write a script that can poll OpenWeatherMap‘s public API and grab information about real-time wind speed and direction information about any given set of coordinates.3 This renders quite an impressive image, though to do this for some 1,154 targets requires a lot of RAM (about 1.5 GB) and a fast computer. So it’s not something one wants to necessarily do all the time.

I have captured the results as a series of interactive screenshots, to better save you (and your web browser) the trouble of trying to render these yourself. You can see how changing the yield dramatically changes the fallout (assuming surface bursts, of course). The interactive viewer is available by clicking the image below, or this link.4

Screenshot of my interactive viewer for the nuclear war plan. Click to view.

Screenshot of my interactive viewer for the nuclear war plan. Click to view.

I also sampled weather data from a few days in a row, to see what differences it made from a practical standpoint. It is remarkable how different wind speed and direction can vary from day to day. In some of these “simulations,” Copenhagen, Denmark, avoids fallout. In others, it does not. Under some weather conditions (and yield selections), northern Japan gets some fallout from an attack on the Soviet-controlled Kuril Islands; in others, it does not. The NUKEMAP’s fallout estimator is, of course, a very simplified model, but even with that you can get a sense of how much difference a shift in the winds can make.

Having done that, I started to wonder: what would the casualties of such an attack look like? I don’t have population density data of the relevant areas from 1956 that has sufficient granularity to be used with my normal NUKEMAP casualty estimating script, but I figured that even the present-day population figures would be interesting. If you try to query the casualty database with over a thousand targets it just says “no,” so I wrote another script that would query it target-by-target and tally the results.

The results were a bit staggering. I mean, I assumed it would be a large number. But they are really large numbers. Some of this is because the casualty script is double-counting “victims” when they are inside the relevant blast areas of multiple detonations. At the moment, there’s no easy way around that (even for a small number of detonations, keeping track of who is already “dead” would require a lot of time and processing power, and to do it on the scale of a thousand is just not possible with the way it is set up currently).

An example of an area where a lot of "double-counting" is taking place — St. Petersburg. The circles show various pressure rings for 1 Mt weapons, which are used by NUKEMAP to calculate casualties. Maybe just a little overkill...

An example of an area where a lot of “double-counting” is taking place — St. Petersburg. The circles show various pressure rings for 1 Mt weapons, which are used by NUKEMAP to calculate casualties. Maybe just a little overkill…

On the other hand, the casualty estimate does not take into account fallout-related casualties, or the long-term casualties caused by the destruction of so much infrastructure. The target list also doesn’t tell us how many targets were, in fact, targeted redundantly with multiple weapons — the idea that it might have been “one nuke, one target” is definitely an incorrect one. Even before World War II had completely ended, US planners for nuclear war against the Soviet Union understood that not every bomb would make it to a target, and so planned for multiple weapons to be targeted on each. So “double-killing” those people in some of these locations is probably not so wrong. It likely isn’t all that crazy to think of these numbers as back-of-the-envelope estimates for what would result if you waged this kind of attack today (which is not to imply that the US would necessarily do such a thing). But I don’t want anyone to think I am implying any kind of real certainty here. I would, in fact, be dubious of anyone, at any time, implying a lot of certainty about these kinds of things, because we (fortunately) lack very much first-hand experience with this kind of “data,” outside of the results at Hiroshima and Nagasaki, which were in many ways particular to their time and place.

Casualty figures, of course, require making assumptions about the size of the nuclear weapons used, as well as the fuzing settings (airbursts generate far less downwind fallout in comparison to surface bursts, but they can greatly increase the casualties for people in civilian structures). For 1956, there would have been a “mix” of yields and types of weapons. We don’t have data on that to my knowledge. As a simplifying assumption, I just ran the casualty calculation with a number of yields, and with both surface burst and airbursts (optimized to increase the range of the 5 psi blast area) options. For the sake of space and avoiding the appearance of false precision, I have rounded them to their nearest million below:

surface burst airburst
injuries fatalities injuries fatalities
10 Mt 259 239 517 304
5 Mt 210 171 412 230
1 Mt 120 70 239 111
500 kt 89 46 185 77
100 kt 39 16 94 30
50 kt 25 10 66 19

At first I thought some of these numbers just seemed fantastical. Russia today only has a population of 140 million or so. How could we get up to numbers so high? Some of this is, again, because of double-counting, especially with the very big bomb — if you run a 10 Mt bomb on Moscow kills 5.5 million people, and injures 4 million, by NUKEMAP’s estimate, which combined is 70% of the 13 million people in the area of the 1 psi blast radius of such a weapon. (If that seems high, remember that a 10 Mt bomb goes well outside the city of Moscow itself — the Great Moscow Metro Region is about 16 million people total.) Since a large number of nukes were targeted around Moscow, that’s a lot of double counting, especially when you use them with such high-yield weapons.

So the very-big numbers I would take with a very hefty grain of salt. NUKEMAP’s casualty estimator really isn’t meant for guessing multiple, overlapping damage areas. At best, it attempts to give back-of-the-envelope estimates for single detonations. Separately, the US arsenal at the time was around 10,000 megatons worth of destructive power. So they obviously couldn’t have been (and wouldn’t have been) all multi-megaton monsters. But, all the same, I don’t think it’s at all improbable that the multi-megaton monsters that were in the arsenal would have been targeted at heavily populated regions, like Moscow. Especially given the fact that, again, there would have been multiple nukes aimed at each target.

I also thought it would be interesting to take the casualties and break them apart by region. Here’s where I found some really startling results, using a 1 Megaton (1,000 kiloton) airburst as my “model” detonation, again in millions:

injuries fatalities
Soviet Union 111 55
Warsaw Pact 23 10
China + North Korea 104 46
239 111

To make this point more clearly: 820 of the 1,154 targets were inside the Soviet Union proper. They are responsible for 48% of the casualties in the above scenario. Non-Soviet countries in the Warsaw Pact (Eastern Europe, more or less), were responsible for “only” 188 of the targets, and 9% of the casualties. China and North Korea had only 146 of the targets, but were accountable for 43% of the casualties. Which is to say, each “detonation” in the USSR on average produced around 203,000 casualties on average, each one in Eastern Europe around 176,000, and each one in Asia is over 1 million. That’s kind of bananas.

Now, these use modern (2011) population density figures, not those of 1956. But it’s still a pretty striking result. Why would this be? Partially because the Asian targets seem to be primarily in large cities. Many of the Soviet targets, by contrast, are of pretty isolated areas — remote military airfields in some cases — that only kill a few hundred people. It would make for a very interesting study to really get into the “weeds” of this target plan, and to sort out — systematically — what exactly was being targeted in each location, as best as we can. If we did that, we’d possibly be able to guess at whether an airburst or a surface burst was called for, and potentially even be able to judge target priorities, though the “bomb-as-you-go” method of attack used in the 1950s probably means that even low-priority targets would get nuked early on if they were on a path to a higher-priority one.

Total megatonnage of the US nuclear stockpile — nearly 10 gigatons by 1956, climbing to a peak of over 20 gigatons in 1959. Source: US Department of Energy

Total megatonnage of the US nuclear stockpile — nearly 10 gigatons by 1956, climbing to a peak of over 20 gigatons in 1959. Source: US Department of Energy

What does this exercise tell us? Two things, in my mind. One, this 1956 target list is pretty nuts, especially given the high-yield characteristics of the US nuclear stockpile in 1956. This strikes me as going a bit beyond mere deterrence, the consequence of letting military planners have just a little bit too much freedom in determining what absolutely had to have a nuclear weapon placed on it.

The second is to reiterate how amazing it is that this got declassified in the first place. When I had heard about it originally, I was pretty surprised. The US government usually considered target information to be pretty classified, even when it is kind of obvious (we target Russian nuclear missile silos? You don’t say…). The reason, of course, is that if you can go very closely over a target list, you can “debug” the mind of the nuclear strategist who made it — what they thought was important, what they knew, and what they would do about their knowledge. Though times have changed a lot since 1956, a lot of those assumptions are probably still at least partially valid today, so they tend to keep that sort of thing under wraps. These NUKEMAP “experiments” are quick and cheap approaches to making sense of this new information, and as the creator of the NUKEMAP, let me say that I think “quick and cheap” is meant as a compliment. To analyze something quickly and cheaply is to spark new ideas quickly and cheaply, and you can always subject your new ideas to more careful analytical scrutiny once you’ve had them. I hope that someone in the future will give this target data some real careful attention, because I have no doubt that it still contains many insights and surprises.

  1. Because there has been some confusion about what this list is, I want to clarify a bit here. It is a “Weapons Requirements Study,” which is to say, it’s the way in which the US Air Force Strategic Air Command said, “here are all the things we might want to nuke, if we could.” The might and if we could parts are important, because they are what makes this difference from an actual war plan, which is to say, “what we would actually do in the event of a nuclear war.” The might means that not necessarily all of these targets would have been nuked in any given war situation, but indicates the sorts of things that they considered to be valid targets. The if we could means that this would require more weapons than they could afford to use at the time. In 1956, the US stockpile contained “only” 3,692 warheads. This target list is meant to imply that it needed to be bigger, that is, that by 1959 they would want more weapons to be produced. So by 1959 they had 12,298 weapons — more than three times as many. Why so many weapons for the same number of targets? Because, as noted in the post below, the idea of one-nuke, one-target isn’t how they planned it. Anyway, the long and short of it is, this isn’t exactly the same thing as a war plan, much less for 1956. It may over-count, but it also probably under-counts (because it ignores tactical use, targets of opportunity, the overkill that would occur when targets were multiple-targeted, etc.). But it does give you a flavor of the war planning that was going on, and is probably closer to that than any other document that has been released for this time. As for how that would affect what would have happened in 1956, it’s hard to say, but this is in line with many of the other things we know about nuclear war planning at that time, so I think it is a fair illustration.
  2. I think my students were probably the most happy that FLI digitized all of this target data because if they hadn’t, I was going to force my undergrads who take my data visualization course to do it in the name of a practical example of what “crowdsourcing” can mean.
  3. In some cases, OpenWeatherMap did not have information about some of the coordinates. In such cases, the script averaged the missing point from several surrounding points, weighting them by distance. The results it gives in doing this seem plausible enough. For each time I ran it, there were only about two or three missing pieces of data.
  4. For those who want to look at the dataset themselves, the CSV file that the visualization uses is available here.

Silhouettes of the bomb

You might think of the explosive part of a nuclear weapon as the “weapon” or “bomb,” but in the technical literature it has its own kind of amusingly euphemistic name: the “physics package.” This is the part of the bomb where the “physics” happens — which is to say, where the atoms undergo fission and/or fusion and release energy measured in the tons of TNT equivalent.

Drawing a line between that part of the weapon and the rest of it is, of course, a little arbitrary. External fuzes and bomb fins are not usually considered part of the physics package (the fuzes are part of the “arming, fuzing, and firing” system, in today’s parlance), but they’re of course crucial to the operation of the weapon. We don’t usually consider the warhead and the rocket propellant to be exactly the same thing, but they both have to work if the weapon is going to work. I suspect there are many situations where the line between the “physics package” and the rest of the weapon is a little blurry. But, in general, the distinction seems to be useful for the weapons designers, because it lets them compartmentalize out concerns or responsibilities with regards to use and upkeep.

Physics package silhouettes of some of the early nuclear weapon variants. The Little Boy (Mk-1) and Fat Man (Mk-3) are based on the work of John Coster-Mullen. All silhouette portraits are by me — some are a little impressionistic. None are to any kind of consistent scale.

The shape of nuclear weapons was from the beginning one of the most secret aspects about them. The casing shapes of the Little Boy and Fat Man bombs were not declassified until 1960. This was only partially because of concerns about actual weapons secrets — by the 1950s, the fact that Little Boy was a gun-type weapon and Fat Man was an implosion weapon, and their rough sizes and weights, were well-known. They appear to have been kept secret for so long in part because the US didn’t want to draw too much attention to the bombing of the cities, in part because we didn’t want to annoy or alienate the Japanese.

But these shapes can be quite suggestive. The shapes and sizes put limits on what might be going on inside the weapon, and how it might be arranged. If one could have seen, in the 1940s, the casings of Fat Man and Little Boy, one could pretty easily conjecture about their function. Little Boy definitely has the appearance of a gun-type weapon (long and relatively thin), whereas Fat Man clearly has something else going on with it. If all you knew was that one bomb was much larger and physically rounder than the other, you could probably, if you were a clever weapons scientist, deduce that implosion was probably going on. Especially if you were able to see under the ballistic casing itself, with all of those conspicuously-placed wires.

In recent years we have become rather accustomed to seeing pictures of retired weapons systems and their physics packages. Most of them are quite boring, a variation on a few themes. You have the long-barrels that look like gun-type designs. You have the spheres or spheres-with-flat ends that look like improved implosion weapons. And you then have the bullet-shaped sphere-attached-to-a-cylinder that seems indicative of the Teller-Ulam design for thermonuclear weapons.

Silhouettes of compact thermonuclear warheads. Are the round ends fission components, or spherical fusion components? Things the nuke-nerds ponder.

There are a few strange things in this category, that suggest other designs. (And, of course, we don’t have to rely on just shapes here — we have other documentation that tells us about how these might work.) There is a whole class of tactical fission weapons that seem shaped like narrow cylinders, but aren’t gun-type weapons. These are assumed to be some form of “linear implosion,” which somewhat bridges the gap between implosion and gun-type designs.

All of this came to mind recently for two reasons. One was the North Korean photos that went around a few weeks ago of Kim Jong-un and what appears to be some kind of component to a ballistic case for a miniaturized nuclear warhead. I don’t think the photos tell us very much, even if we assume they are not completely faked (and with North Korea, you never know). If the weapon casing is legit, it looks like a fairly compact implosion weapon without a secondary stage (this doesn’t mean it can’t have some thermonuclear component, but it puts limits on how energetic it can probably be). Which is kind of interesting in and of itself, especially since it’s not every day that you get to see even putative physics packages of new nuclear nations.

Stockpile milestones chart from Pantex's website. Lots of interesting little shapes.

Stockpile milestones chart from Pantex’s website. Lots of interesting little shapes.

The other reason it came to mind is a chart I ran across on Pantex’s website. Pantex was more or less a nuclear-weapons assembly factory during the Cold War, and is now a disassembly factory. The chart is a variation on one that has been used within the weapons labs for a few years now, my friend and fellow-nuclear-wonk Stephen Schwartz pointed out on Twitter, and shows the basic outlines of various nuclear weapons systems through the years. (Here is a more up-to-date one from the a 2015 NNSA presentation, but the image has more compression and is thus a bit harder to see.)

For gravity bombs, they tend to show the shape of the ballistic cases. For missile warheads, and more exotic weapons (like the “Special Atomic Demolition Munitions,” basically nuclear land mines — is the “Special” designation really necessary?), they often show the physics package. And some of these physics packages are pretty weird-looking.

Some of the weirder and more suggestive shapes in the chart. The W30 is a nuclear land mine; the W52 is a compact thermonuclear warhead; the W54 is the warhead for the Davy Crockett system, and the W66 is low-yield thermonuclear weapon used on the Sprint missile system.

A few that jump out as especially odd:

  • PowerPoint Presentation

    Is the fill error meaningful, or just a mistake? Can one read too much into a few blurred pixels?

    In the Pantex version (but not the others), the W59 is particular in that it has an incorrectly-filled circle at the bottom of it. I wonder if this is an artifact of the vectorization process that went into making these graphics, and a little more indication of the positioning of things than was intended.

  • The W52 has a strange appearance. It’s not clear to me what’s going on there.
  • The silhouette of the W30 is a curious one (“worst Tetris piece ever” quipped someone on Twitter), though it is of an “Atomic Demolition Munition” and likely just shows some of the peripheral equipment to the warhead.
  • The extreme distance between the spherical end (primary?) and the cylindrical end (secondary?) of the W-50 is pretty interesting.
  • The W66 warhead is really strange — a sphere with two cylinders coming out of it. Could it be a “double-gun,” a gun-type weapon that decreases the distance necessary to travel by launching two projectiles at once? Probably not, given that it was supposed to have been thermonuclear, but it was an unusual warhead (very low-yield thermonuclear) so who knows what the geometry is.

There are also a number of warheads whose physics packages have never been shown, so far as I know. The W76, W87, and W88, for example, are primarily shown as re-entry vehicles (the “dunce caps of the nuclear age” as I seem to recall reading somewhere). The W76 has two interesting representations floating around, one that gives no real feedback on the size/shape of the physics package but gives an indication of its top and bottom extremities relative to other hardware in the warhead, another that portrays a very thin physics package that I doubt is actually representational (because if they had a lot of extra space, I think they’d have used it).1

Some of the more simple shapes — triangles, rectangles, and squares, oh my!

Some of the more simple shapes — triangles, rectangles, and squares, oh my!

What I find interesting about these secret shapes is that on the one hand, it’s somewhat easy to understand, I suppose, the reluctance to declassify them. What’s the overriding public interest for knowing what shape a warhead is? It’s a hard argument to make. It isn’t going to change how to vote or how we fund weapons or anything else. And one can see the reasons for keeping them classified — the shapes can be revealing, and these warheads likely use many little tricks that allow them to put that much bang into so compact a package.

On the other hand, there is something to the idea, I think, that it’s hard to take something seriously if you can’t see it. Does keeping even the shape of the bomb out of public domain impact participatory democracy in ever so small a way? Does it make people less likely to treat these weapons as real objects in the world, instead of as metaphors for the end of the world? Well, I don’t know. It does make these warheads seem a bit more out of reach than the others. Is that a compelling reason to declassify their shapes? Probably not.

As someone on the “wrong side” of the security fence, I do feel compelled to search for these unknown shapes — a defiant compulsion to see what I am not supposed to see, perhaps, in an act of petty rebellion. I suspect they look pretty boring — how different in appearance from, say, the W80 can they be? — but the act of denial makes them inherently interesting.

  1. One amusing thing is that several sites seem to have posted pictures of the arming, fuzing, and firing systems of these warheads under the confusion that these were the warheads. They are clearly not — they are not only too small in their proportions, but they match up exactly to declassified photos of the AF&F systems (they are fuzes/radars, not physics packages).