Geoff FordenNorth Korea’s Design Choices

The DPRK apparently told China before its 2006 test that they were aiming for a yield of about 4 KT but they only acheived a yield around ½ KT. This implies that there was a significant problem with that design. ( Their announcement of this test seems to indicate that they are acknowledging that.) If this time they had gone with a test of a 20 KT design, as the Russians are apparently saying, it means that they were changing designs to ensure they got a big bang and avoided the publicity problems they went through after the 2006 test: of having their first test a failure.

If its yield really is closer to 4 KT, it is, of course, still possible that it was a 20 KT design that failed (which seems rather hard to believe since 20 KT is the “easiest” yield to get—that’s why it was used in the first plutonium bomb during WWII). But its also possible they were once again aiming for a 4 KT yield. That would mean they kept the basics of their old design and just corrected whatever the problem was. This would show a certain level of sophistication of project management that is not obvious in their missile development program. (That assessment, of course, depends in part on what the 2006 Tae’podong II looked like.)

If they had gone with the “fail safe” WWII design, it would probably mean it was too heavy to mount on a missile. They would be making a political bomb that would undoubtedly use a lot of high explosive to ensure it got a good compression of the plutonium pit. The 4 KT bomb, however, might very well fit on a DPRK missile. If they have stayed with this design, it probably indicates that weaponizing it is even more important than ensuring a successful test.

Comments

  1. GWR (History)

    Good assessment (this site was my first visit when I heard the news). Could you speculate on the quantity of plutonium that the DPRK has now used in the two tests and, given assessments as to how much they have on hand, where that leaves their stocks now.

  2. Tim

    Doesn’t it also show a fair degree of technical sophistication to find the flaw with (likely) not that sophisticated instrumentation of the first test?

    If they can get a 4kt device right on the second try, that seems to me to imply their nuclear physicists are quite a bit better than I feel comfortable with …

  3. Geoff Forden (History)

    Good questions GWR! Unfortunately, it would take some work on my part (and today is the nicest day of the 3-day weekend) but perhaps some of our wonk-readers know. (My first guess is that the 4 KT design might use more Pu than the 20 KT bomb in order to compensate for using less high explosive. If thats true, the two bombs might each use more than 8 kg of Pu.)

    I known exactly how you feel, Tim. And now, off to enjoy the sunshine and stop thinking about mega-death for at least one afternoon.

  4. George William Herbert (History)

    Some of us have been chattering in email. I was up looking at seismographs shortly afterwards and mostly frustrated by the low signal.

    My own impression all along was that the first test yield indicated a marginal test or marginal failure of a compact design intended for a missile warhead. Probably unboosted tests of a design intended to boost to higher yield.

    A 20 kt design which is 4 kt without boosting and is compact enough for known NK missile warhead sections isn’t that hard to conceptually design. The warhead sections are big enough to do it with a multipoint spherical system.

    Many modern US primaries (and by modern, I mean early 1960s vintage designs) get around a kiloton unboosted, around 10 kilotons boosted, and use that as a primary for a multistage weapon. They by all accounts use less than 5, perhaps as little as 3.5 kilograms of WGPu. The whole primary assembly fits within a diameter of no more than about 30 cm – probably 25 cm, as multistage fusion weapons of 30 cm outer casing diameter are known, and the casing and lenses are not infinitesimally thin.

    A NK weapon would presumably use RDX or HMX based explosives instead of insensitive / fire-safer TATB in western designs. That means more HE energy in the same mass/volume. Using a spherical system with the same lens geometry properties as Fat Man, you end up with about 50% additional diameter around the spherical working driver HE sections.

    I just started to write then deleted a “working back from there with significant margins” explanation here which more or less would give you the Iraqi bomb design, in the interests of not annoying those who sincerely believe in RD being sacrosanct, but you can trivially fit 3-4 times the explosive energy US weapons of 30 years ago used plus first-generation class multipoint lenses in the nose cones in question, without using better lenses (92-point, ring lens, etc) or moving away from multipoint systems.

    This really isn’t as hard as people make it out to be. A lot of NP policy experts are really quite naive on this point. Tiny is hard – small enough to be useful is much easier.

  5. Geoff Forden (History)

    I’m always amazed by people who toss around the “Iraqi design.” I’ve read the Iraqi nuclear CAFCD—at least that version that was scrubbed for inspectors who do not come from nuclear weapons states or who don’t have a need to know design information, which is very proliferation-sensitive stuff—and even I don’t know what the Iraqi design looked like. So I have to be very skeptical about claims of conceptual designs that appear very similar to the Iraqi design. (Which was a uranium implosion device.) There were also very good reasons why the US designs from the 60’s came twenty years after the Fat Man design. So I wish that those people who are less naïve than I am would be more specific about some of these things.

  6. Azr@el (History)

    Allowing 4kt is their target yield, to what end? 4kt tossed across the pacific on a first or second generation ICBM does not deter so much as enrage. The end result would no doubt be much like addressing law enforcement officers with a BB gun.

    4kt works as a tactical munition, meaning the DPRK might be interested in a usable battlefield weapon to balance out the South’s qualitative advantages. 4kt is also in the ballpark for driving a ~40-400kt H-bomb hohlraum. Insight into the chemical explosive drivers should resolve where the DPRK is heading, either way the design for both applications would be fairly low in mass.

  7. Carey Sublette

    Azr@el:

    The prospect of a 4 kt bomb exploding in the heart of Seoul or Tokyo, which would kill tens of thousands at least, and do hundreds of billions of dollars in damage, would have a very powerful deterrent effect on those nations, and through their influence, the United States. Enough effect to entirely foreclose plans to use military force against the DPRK.

    (In the near term hitting the U.S. directly is simply not an option for them. They don’t have the technology yet. They do have the technology to hit these nearer and richer ones.)

    It is a mistake to project standard major power defintions and doctrine on to the DPRK arsenal. With the proper delivery systems and doctrine even a 4 kt bomb can be strategic weapon.

  8. Allen Thomson (History)

    > design intended to boost

    A point of detail, but would NK have any problem getting the required amounts (grams?) of tritium?

  9. Stephen Young

    Azr@el, please tell me you are kidding. 4kt on Seoul or Tokyo probably kills more people than died in Hiroshima or Nagasaki, simply because of population density. It is a deterrent.

  10. David (History)

    QUESTION: Where does the 4kT number come from. I tried following the links in the post but I didn’t see the 4kT number reported anywhere but in ACW posts (not that I don’t trust ACW, but I was hoping for a citable reference).

    One quick response to Azr@el:

    Yes if NK lobbed 4 kT over the pacific the US would make NK disappear. But what if NK has a 50/50 shot of putting 4 kT’s over LA? Do you think such a chance would change any US President’s thinking?

    Yes, 4 kT is small compared to 50 MT. But its still a plenty big boom in the middle of a major city (or any city).

    Yes, there are a lot of assumptions in the line of reasoning, but a deliverable 4 kT warhead is more than enough to change the strategic calculus.

    My 2 cents anyhow.

  11. Zak Johnson (History)

    I’ve really enjoyed reading all of your posts. I’ve been interning at the CTBTO and it has been very exciting to say the least. So here’s my two cents.

    It seems like a low-yield weapon would be much more practical for the DPRK. The cultural ties between the North and the South are very strong, so it seems unlikely that they are aiming to wipe their neighbors off the map. Instead, low-yield weapons could let them choose their targets. As strange as it seems, DPRK leaders could view this type of weapon as a tool to “liberate” their brothers from the clutches of American tyranny. Their real problem seems to be lack of fissile material. According to Sig Hecker’s testimony to the Senate FR Committee – The DPRK claimed to have reprocessed all 8000 fuel rods to extract plutonium metal during one continuous campaign between mid-January 2003 and end of June 2003. The 8000 fuel rods are estimated to contain up to 25 to 30 kg of plutonium metal.

    Here is an interesting quote I found in a paper about the CTBT:

    “Siegfried Hecker, former Director, Los Alamos National Laboratory, stated that the North Korean weapon designers most likely did not test a Nagasaki-type device (a basic implosion device) because they could have had high confidence, without testing, that such a device would work. Instead, his analysis is that the North Koreans most likely tested a… Read More more advanced design, even at the risk of partial failure, which is what the seismic signals appear to confirm. He considers it highly unlikely that they intentionally designed a mini-nuke. However, even if the test was not fully successful, he believes they learned much from the test.”

    Thanks again for all the great posts!!

  12. George William Herbert (History)

    Re Tritium…

    They had a reactor. It was being run to produce WG Pu. Sticking a rod of lithium down in there and capturing the tritium that comes out isn’t exactly rocket science.

    The IAEA inspectors presumably could know the real answer. But they haven’t said publically that I know of.

  13. Geoff Forden (History)
  14. David (History)

    Thanks Geoff!

  15. Geoff Forden (History)

    No George, extracting tritium isn’t exactly rocket science. Its very complicated chemistry. This is the problem with your conceptual designs. They totally ignore the practical difficulties of learning to do something; a process that is usually slow and pains taking as you learn what are known as the tacit skills. The details of extracting tritium from lithium rods on an industrial scale are military secrets but here is an extract from a patent on a lab scale process:

    The gas released during the extraction step just described may contain small amounts of oxygen and nitrogen and always contains relatively great amounts of helium and hydrogen. In order to free the tritium from these contaminating and diluting gases, according to the process of this invention, the mixture is first passed over uranium, which, for instance, is in the form of turnings, at a temperature of about 800° C. whereby nitrogen and oxygen are removed. Thereafter the remaining gas mixture is separated by a palladium valve having a temperature of from 350° to 400° C. whereby the hydrogen isotopes are adsorbed and diffuse through the palladium while the helium remains unabsorbed. During this step, a vacuum is maintained at the outlet side of the palladium valve so that back-diffusion of the tritium into the valve is prevented. This may be done by pumping the tritium containing gas, e.g. into a product gas measuring system. The product gas consists essentially of tritium and hydrogen, the latter mainly formed by the side reactions discussed in the introductory part of this specification. Hydrogen and tritium finally may be separated, if desired; this is preferably done by a thermal diffusion separation method.

  16. Jan Vaněk jr. (History)

    Actually, the URL doesn’t work – bloody CMS changed two successive hyphens into an endash; one has to fix it manually. Anyway, the article says only “North Korea purportedly informed China that the anticipated yield from the test would be approximately four kilotons” without giving any specific source either 🙁

    You know, I came here from a Czech website that summarised the post – see Google back-translation , just about comprehensible. They claim that you “convincingly argue” that DPRK went for the 20kT WWII design, which is too heavy to deliver and thus (they conclude) there is no acute danger and need for the international community to rush the response. However my reading is that you consider the other possibility of their successfully debugging the light 4kT implosion device if not equally, at least comparably probable; am I right?

  17. Geoff Forden (History)

    Jan, I actually tried to simply lay out the two possibilities as I saw them at the time. I had intended it to be an “if this then that” sort of thing. As the yield estimates seem to converge on 4 kt, then I am leaning more and more toward the “weaponize more important than political consequences” hypothesis.

    As much as I hate to disagree with anybody who says I argued anything convincingly, I think that your interpretation is right. Of course, it is always the writer’s fault if the reader doesnt understand exactly what is meant.

  18. Azr@el (History)

    I’ve seen nothing openly suggesting North Korea’s possession of a tritium refinement capability. But of course such a thing can be completely concealed given it’s small scale nature. But even then the DPRK would have to forgo some Plutonium production in order to breed tritium. That same blanket composed of Lithium could be composed of Thorium or U238, the scarcity of neutrons, of the right energy level, forces this opportunity cost situation.

    But say they make this call, or have managed to secure another source of tritium, i.e. the IRI, they could conceivable forge a Pu240 heavy Pu239 boosted device of roughly 4kt with less than 2.5kg of reactor grade plutonium and half a gram of Trit. The only reason such a heavy driver device would be appealing to them in lieu of just breeding more PU239 and using a smaller driver is perhaps they’d rather just utilize reactor grade plutonium without the hassle of removing the PU240.

    Also perhaps we should be thinking outside the box on the driver.

    As far as some overstating the strategic deterrence of 4kt; do not assume the DPRK has anywhere near the CEP on their “ICBM—” to target a city with sufficient precision to slag a densely populated quarter as opposed to boiling some water or making green glass in the desert. Further do not discount the potential for great ruthlessness from those who adorn the oval office. We like to assume we are the civilized ones, but history will attest otherwise and I’m sure the DPRK leadership fully understands that you do not deter the “liberators” of Hiroshima and Nagasaki with firecrackers.

  19. Carey Sublette

    Azr@el suggests:
    “As far as some overstating the strategic deterrence of 4kt; do not assume the DPRK has anywhere near the CEP on their “ICBM—” to target a city with sufficient precision to slag a densely populated quarter as opposed to boiling some water or making green glass in the desert.”

    Two points:
    1. The DPRK does not have delivery systems capable of striking the U.S., but they can threaten its allies South Korea and Japan. The range to Tokyo is about 1000 km, and a 10 km CEP still allows the bomb to go off inside the city with high probability. Even the DPRK should be able to do better than a 1% error. And Seoul is just over the DMZ.

    2. Deterrence does not require the DPRK to ever hit anything anywhere. It just has to present a plausible claim that it can.

  20. George William Herbert (History)

    Geoff – I’m sorry if my answer came off as blase again.

    The tritium extraction process from the Lithium rods and its purification are not the sort of thing your average mad scientist could do at home, no. But the chemistry, physics, and process issues are not hyperclassified and the problem is simple compared to for example Plutonium extraction from reactor spent fuel (which North Korea clearly has accomplished).

    There is a lot of physics, chemistry, and industrial engineering associated with a full up nuclear weapons program, in addition to the design and coming up with the fissile material.

    Most of the details are fairly straightforwards in a scientific and engineering sense – they take time, money, people, but the solutions are known theoretically and industrially, and the hardest part (figuring out if it can be done) are accomplished.

    In the totality of the scope of industrial engineering problems in a weapons program, including Uranium production, reactor, hot cells for Pu extraction, explosives production, etc., the Tritium production is a relatively inexpensive small scale operation. It operates as an adjunct to a reactor program, not interfering with the reactor basic operations in any significant way. The extraction issues and processing are nontrivial but much lower complexity, processed material mass/volume, and chemical and radioactive hazard. They have / had the major capital item (functional reactor) and had people capable of many more, many harder chemistry and physics and industrial engineering tasks.

    We know the North Koreans already figured out how to run the 40 yard dash, do the longjump, and pole vault in their nuclear program. Tritium production is taking a sprint up the stadium bleacher steps.

    It’s easy to skip over detail discussions of the industrial engineering involved – nobody is seriously bothering to address it in the blogosphere at the moment, North Korea obviously passed the taller hurdles and was only “intent to weaponize” and “successful test program” away from a nuclear arsenal for about the last decade. In that context, the “do they have Tritium” question is adequately answered by “Would they want to have Tritium?” – which is a fairly obvious “yes”. Anyone who can build a reactor, extract weapons grade Pu, and so forth should be able to produce Tritium in weapons program useful quantities without significant additional difficulty.

  21. Azr@el (History)

    Mr. Sublette grants far more benevolence and compassion to U.S. leadership than history warrants. Nippon and the ROK are very important allies, equivalent in importance to West Germany during the Cold War, the same West Germany our intentions would have seen an atomic beaten wasteland in hopes of containing a breakout by the Soviet 8th Guards Army. In the same very cold vein, the DPRK holding at risk Seoul or Tokyo with a tactical atomic would fail deter the U.S. and forlorn would be the faith placed in the U.S. flinching for fear of manageable harm befalling our North East Eurasian allies should push come to shove. The DPRK, which must stake it’s very existence upon our philosophical musings fully understands that deterrence derives from the potential to kill not the potential to harm, especially not the potential to harm a third party lacking a veto in U.S. decision making.

  22. Allen Thomson (History)

    > The details of extracting tritium from lithium rods on an industrial scale are military secrets but here is an extract from a patent on a lab scale process:

    Wow. I realize now more than ever that I’m not a physical chemist: why not use fractional distillation/ freezing for all of the steps except the last one?

  23. Azr@el (History)

    Extraction of tritium from TPBARs is not a military secret, the process is fairly well understood. If the DPRK wishes to produce tritium, it can, but to do so would be to forgo some degree of plutonium production. These nuclear transmutations are neutron hungry and the DPRK would be forced to trade off Pu239 production to produce trit.

    Under what circumstances would such a young program make such a leap? Not the non-trivial development of tritium extraction, but the heavy lifting to develop a boosted design; not an easy bit of computational physics nor attendant engineering.

  24. Geoff Forden (History)

    Az@el, if you would, then please answer Allen’s question. I’m not a physical chemist either. (I tend to take things like the Kirk-Othmer Encyclopedia of Chemical Technology at face value, hence my comment about military secrecy.)

  25. Azr@el (History)

    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3C-4SY6YFG-5&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=efee2f4e268ff41e78d895f46630855e

    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3C-4T0X2P0-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=304014752dd24d9a5d95edbfcb91ddf3

    Large scale tritium recovery is an essential component of a fusion DT economy being commercialized. None of this is classified nor has been for a very long time; decades since anyone cared about controlling this sort of information. As of 2008, I could have exported, above board, 100 individual orders of readily available tritium not exceeding 4.12 milligrams per purchase; enough to boost 2.5kg of plutonium. The main hurdle is actually engineering a device that can initiate a fast burn of tritium-deuterium during the assembly time of the fissionable material. Setting off a sufficiently large fusion burn in the shell of a collapsing fission bomb is not a walk in the park sort of things. Instead of using half a gram efficiently, you may wind up putting in a few grams and accepting a very inefficient autocatalytic coupling.

    My apologies if my tone is dreary, first the DPRK sets off an atomic and now Manchester United loses to Barca; definitely not my week.

  26. Geoff Forden (History)

    Allen, Im going to leave it to you to look up Azr@el references to find the answer to your question.

  27. Azr@el (History)

    I believe the article in question is the 13th of February 2004 one by Joseph J. Katz of Argonne National Laboratory.

    “Because of the military importance of tritium, details of the large-scale production of this isotope have not been published. A report, however, is available that describes the large-scale production of tritium and its uses in France (48).”

    Which references “Le Tritium, Commissariat a l’Energie Atomique, Bull. Inform. Scientifiques et Techniques, No. 178, Feb. 1973.”

    Mr. Katz Obviously did not bother to peruse the Kirk-Othmer Encyclopedia of Chemical Technology or he would have stumbled upon this 4th of December 2000 article by Edward Von Halle on Isotope Separation which states:

    “A plant has been built and is in operation for the simultaneous extraction of
    hydrogen and tritium from heavy water (20). In this plant, low temperature rectification of liquid hydrogen at 150 kPa (1125 torr) is used to accomplish isotopic fractionation.”

    Which references P. Pautrot and M. Damiani in ACS Symp. Ser. 68, (1978)., 163–171. which details large scale production of tritium thru a method similar to the one Allen Thomson eludes to.

    It is a trivial matter to apply, with a little ingenuity, the techniques for separation of tritium from the moderator fluid of a heavy water reactor to the retrieval of tritium from punctures of TPBARs, though it may prove very non-trivial to acquire the principal techniques.

    From this we can conclude that if you read French, Tritium separation techniques were available to you from as early as 73’ and for the English speaking world, a fairly good insight into these techniques presented themselves early as 78’, i.e. three decades ago.

  28. Carey Sublette

    I am not going to get into a debate with Azr@el over his/her views supposing U.S. casual disregard of its formal treaty commitments to allies, and unconcern at the prospect of catastrophic mass murder in the capitals of its two most important Asian allies.

    But I do want to make two more points:
    1. War plans of the 1950s and early 1960s to stop a Soviet attack in Europe – seen as an existential threat to the West at a time when conventional defense seemed impossible – are a poor guide to U.S. policies and actions now. None of the considerations present then are operative today.

    2. A 4 kt bomb in the middle of downtown Tokyo would, in round numbers, kill 100,000 maim at least 200,000 more, and do a trillion dollars in damage. A bomb in Seoul would be nearly as bad. Together they would be on the scale of perhaps 60 “9-11s”. To suppose that this would not be viewed as a constraint on U.S. actions in confronting an nation that literally poses no threat to the U.S. today, suggests views not grounded in observable U.S. behavior in the present day.

  29. Azr@el (History)

    It could be said, without taint, that Israel’s well being holds disproportionate sway over U.S. decision making. And yet, when push came to shove in a conflict with a “nation that literally poses no threat to the U.S.” irrrespective of time period, the U.S. rather then disengage from the conflict to preserve Israeli lives, then held at risk by the threat of biochemical missile strike, chose to casually send over a missile defense system that did not work and press on hoping that nuclear deterrence would stay the hand of Iraq’s leadership.

    Of course, this was nearly 2 decades ago and perhaps these views are no longer “grounded in observable U.S. behavior in the present day”. Yet, I would caution that history becomes an incomprehensible mishmash of nonsense when viewed thru the lens of propaganda and wishful thinking, but oddly enough it does seem to make significantly more sense when you accept that at the nation-state level there are no good guys just imperfect interested parties.

    I earnestly hope that no one actually viewed the cold war, especially in hindsight, as an existentially conflict. The Soviet and ourselves postured, but we had no plans for occupation of the Soviet heartland nor they plans for an occupation of North America. Both sides understood, this was a conflict to settle who would garner control of planet, which had been divvied up all but in name between they and us upon the ashes of Deutsch Reich, Nipponese Empire and the collapse of the Far West Eurasian mercantile empires. And should any doubt my words, all you need do is take a trip to Russia. They ended the Cold War by just walking away, no U.S. occupation of Moscow, unless you consider McDonald’s to be as much a threat as do I. We were prepared to have a limited nuclear exchange, lose millions of Americans lives, cover large parts of Eurasia in radioactive ash, including our client states, to achieve what we have now; unipolarity. Be impressed by the steel of leaders that saw thru this decades long goal and yes feel sorry for the sods who fell for and then fell fighting the “Red Menace”, “The Bolshevik Invaders”, fill in your favorite slogan here.

  30. Carey Sublette

    As I said: no debate (to spare the other readers of this blog).

    […]

    But the point remains: even a 4 kt bomb is a potent strategic weapon. I very much doubt that the North Koreans view it in any other light.

    {note added by moderator (GF): I have taken the liberty of editing some of the content of this posting as I believe it could lead down a road that simply inflames the debate without adding an new information. If I’ve missed some previous content that also does that, I apologize.}

  31. Carey Sublette

    Fair enough for the edit, but instead one observation, since Azr@el reveals the apparent source of his/her belief in U.S. disregard for threats to allies: the Desert Storm Scud attacks on Israel.

    Iraq had the capability of delivering some dozens of nerve gas warheads, each holding a few hundred kg of agent, against Israel (throwing in “bio” sounds scary but is a non-existent threat category with respect to Iraq). Israel had good civil defense preparations against the threat, and so the U.S. was risking the potential death of dozens of Israelis.

    The difference in scale between that threat and the effect of a nuclear explosion, against which similarly effective defenses do not exist, is staggering.

    Nuclear weapons are in a class by themselves, and discussion of “weapons of mass destruction” are led astray if this fact is not recognized.

  32. Andy (History)

    Azr@el,

    Some very curious statements on the US attacking North Korea. I wonder if you have any evidence at all to support that? After all, there was a time when the US had nukes in South Korea along with a much larger conventional presence. Now the US nukes are gone, US troops are no longer on the DMZ (and are much smaller in number), and leadership and wartime command-and-control of combined Korean forces is in the process of being transferred to the South Koreans. The US military threat to North Korea has decreased over the last couple of decades, not increased. At the same time, those thousands of North Korean artillery pieces can still range Seoul and the North retains much of their conventional strength, which is still forward deployed along the DMZ.

    And unlike Iraq in 1991, North Korea is not threatening the world’s more important strategic resource. There is not much of value in North Korea for an invader except a multi-trillion dollar bill for reconstruction and reintegration – one that will make the German unification look like peanuts. Neither South Korea nor China, nor the US wants to deal with that, which is why the former too are so eager to always provide enough aid to prevent the collapse of the North Korea.

    Then there is the not-insignificant problem that the bulk of US ground forces are not available and even if they were, South Korea would have to be on board to host an invasion force – not very likely at all.

    So, what, exactly, is your worry? North Korea doesn’t need a nuke to deter a US invasion – it needs nukes because it has little else of strategic consequence (excepting the threat of state collapse and the resulting humanitarian disaster). It needs nukes in order to negotiate/extort concessions from outsiders to ensure regime survival. So the nukes, IMO, are not about military deterrence at all, but a policy of regime survival through extortion.

  33. David (History)

    One more post on the strategic impact of 4 kT weapon in the hands of NK. MODS feel free to edit/delete this post if you feel necessary. My intent isn’t really to engage in debate (opinions rarely are changed over the internet) but just to make a few points that I think are pertinent.

    It was correctly pointed out that my previous post suggesting NK could target LA was a stretch. I thought I had admitted as much initially. The question was when does the threat to LA (or any US city) become non-negligible. At that moment the strategic balance is altered. Personally I can’t imagine anyone at the White House being willing to take any more than a 5% risk that LA could be hit without changing US behavior on the issue. Is DPRK there yet? No. Are they closer? yes.

    Forgetting about crossing the Pacific. Let’s also assume that U.S. interests lie solely with U.S. citizens. There are currently about 30K U.S. troops stationed mainly in and around Seoul. I think that the fate of these troops, especially when considering nukes, would weigh heavily on any US president. For comparison globalsecurity.org reports ~5000 US troops dead as result of the recent Iraq conflict.

  34. Geoff Forden (History)

    Let me clarify my role: Please feel free to disagree with me or any one else on these posts as long as it doesn’t consist of comments that are or can be viewed as personal attacks. I acted preemptively, perhaps, on my edit above but I thought that it might lead down a path we didn’t want the discussion to go. There have been many views here that I disagree with but I try to think of them as an opportunity to understand the thoughts of someone who completely disagrees with me. (If I haven’t always succeeded in having such an Olympian detachment, I’m sorry. Its a goal I strive for.)

  35. Azr@el (History)

    I believe the heart of this “not debate” is a difference of opinion with respect to the nature of deterrence. There seems to be a belief that nuclear weapons in of themselves can act to paralyze a superpower like a magical talisman; a crucifix to ward off vampires if you will. This very much is not the case.

    Take the example of the PRC, they believe that 20 or so 4MT city busters will deter the U.S. or Russia from trying to take a bite out of China. I call this the MSG strategy; make a dish sufficiently unpalatable that no one will wish to sit down at the table. It’s a purely defensive example of deterrence.

    Then perhaps consider the case of the Soviet Union, with thousands of city busters, they still felt they had insufficient deterrence to forestall a U.S. nuclear reaction to them tossing an orgy in Far West Eurasia. This offensive detterence, or Toga Party strategy if you will, is the harder of the two to achieve.

    Thus, in the case of the DPRK, if we assume they are pursuing an MSG strategy, i.e. Defensive deterrence, then they’ve had that for decades. They could burn Seoul to the ground several times over with all the conventional tubes they have on the marches of the DMZ. In fact this has served to deter any attempt by South Korea’s generals for reunification back when this was all the vogue. For the record, the U.S., occupied with more pressing theaters of the Cold War, never cared how many fingers it takes to count the Koreas and thus needed no persuasion to let lying dogs be.

    Imagine that the DPRK is alternatively attempting the Orgy Party Strategy, i.e. offensive deterrence, then clearly that will take a state in their dire economic situation generations to achieve a deliverable arsenal sufficiently massive to neuter a U.S. response to an involuntary reunification of the peninsula. And in the meantime the DPRK would simply implode from the strain, call it an own goal.

    Thus the DPRK’s pursuit of costly nuclear weapons and long range ICBMs most likely arise from a need to address the fear, almost fulfilled by the George the 2nd, of a predatory and bellicose U.S. in the absence of the Soviet nuclear umbrella, thru defensive deterrence. And lo and behold the DPRK nuclear program and their ICBM program both date back to the mid 80’s when Pyongyang first started to have doubts about the stability of Soviet society; what can I say they have better analyst then we do/did. Thus, one day ~decade, we can expect to see a DPRK arsenal of about 20 or so “unha-n’s” ; where n is some positive valued integer greater than 2, armed with about 20 or so 200-400kt ulam-tellers driven by 4kt primaries of unknown design.

  36. Azr@el (History)

    The DPRK is not reacting to our propaganda, whether it be the warm and fuzzy accommodating tone of Obama or the shrill hyperventilating threats of George the 2nd nor is it reacting to the short term disposition of troops or political opinion. Pyongyang is responding to the worst case, from their perspective, scenario derived from the deep inherent potentials in a unipolar world driven by a fairly unrestrained superpower. Much like our contingency planning for invading everything from small Caribbean islands to North Korea itself; we are implementing long cycle procurement and force structure policies to deal with worst case scenarios that may arise unexpectedly irrespective of the supersturcture of propaganda or current short term circumstances, to do otherwise would be negligent.

  37. Ryan Crierie

    I’d like to point something out.

    The Model 1561 and Mark Ones which were initated over Japan had about half of their total weight consisting of armor plate or heavy gauge steel — the threat of Japanese AA fire rendering the bomb a dud as it fell towards the initation point was considered a serious threat.

    Thus, you can make a WWII bomb that weighs about 4,000 to 5,000 lbs; which is reasonably light enough to begin to be placed on missiles, albeit at the limitation of range.

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