Jeffrey LewisNorth Korea’s Juche Rocket

Less than a month ago, we were still getting acquainted with the salvaged chunks and bits of the Unha-3 first stage that South Korea’s Navy had hoisted from the watery deep. It seems that some people have been busy in the meantime, because a multinational, mostly South Korean team of experts (52 of them, by one count) has picked the pieces apart and made determinations about where they come from.

Their answer, for the most part: North Korea.

(Why so quick? The rapid turn-around probably owes something to South Korea’s experience with investigating the destruction of the Cheonan in 2010. They seem to have been ready to get a forensic team in place this time.)

The report was released yesterday in South Korea, but has yet to crop up online. When it does, I’ll post it here. For now, let’s break down what the briefers have told reporters.

1. The frame

According to Yonhap and the Kyunghyang Shinmun, the frame is made of an aluminum-magnesium alloy, AlMg6, produced in North Korea. The report says that the oxidizer tank (above) “was made of several patch panels, which showed poor welding and uneven surfaces, an indication that North Korea seems to have no advanced technology in that area.” But one official qualified this finding, saying, “The welding was not clean and the quality appeared as though it was made with a hammer, but despite the appearance, the technology was not coarse.”

How to square that circle? “Not coarse” may refer to the alloy itself. If this story (in Korean) means what I take it to mean, then it’s now believed that North Korea has started beating sanctions by importing bauxite ore from China rather than aluminum, and is using the ore to produce aluminum domestically. This finding may lend credence to the Asahi’s November 2012 report about an attempted export of high-strength aluminum from North Korea to Burma.

Juche, they call it.

2. The electronics

But not juche all the way. The recovered pieces included between six and ten bits of electronic gear — pressure sensors, temperature sensors, a voltage converter, and wires — that the experts recognized as foreign-made. These pieces were tracked back to five specific countries, four of which were not named for diplomatic reasons. The fifth is China, which I suppose was named for undiplomatic reasons. A source who spoke to The Hankyoreh mentioned that these were portable, dual-use components that “would have been easy to buy, even by someone who was traveling.”

Another source added, “The foreign-manufactured parts are not included in the items that are restricted by United Nations Security Council (UNSC) Resolution 1874, which was passed in 2009, or the Missile Technology Control Regime (MTCR).” This is a fancy way of saying that nothing on this list was really specific to rockets and missiles.

For the curious: MTCR Annex and UNSCR 1874.

Which brings us to something that is specific to rockets and missiles. I speak of

3. The engines

Here’s where the story gets interesting.

It’s been pretty clear for awhile that the first stage of the Unha-3 involves a cluster of four Nodong engines. The Iranians displayed just such a cluster a few years back:

It sure looks prettier before it hits the water. The floral display doesn’t hurt, either.

One or more experts quoted in the news stories were quick to make this connection, but it’s not obvious who owes what technology to whom.

Every discussion that I’ve been party to about the four-Nodong cluster has assumed that it steers the same way that the original Nodong does, with jet vanes. But according to Yonhap, the Hankyoreh, the Kyunghyang, and the Chosun, the report concludes instead that the first stage of the Unha-3 steers with vernier engines. These are small auxiliary engines. (The second stage of Iran’s Safir space launcher uses verniers of a Soviet design to supply its thrust.) In this case, they were unexpected.

The Kyunghyang also reports that the Unha-3 first stage uses a regenerative cooling system. How surprising that should be, I’m not sure. As I might have mentioned, I’m no missile expert.

The bottom line is twofold. First, this engine looks somewhat novel, in the sense that it reconfigures foreign-origin technologies in new and slightly unexpected ways. (Recently overheard: If the Soviet space program was Apple, then the North Korean program is Samsung.) Second, in case you missed it, the experts have judged that the engine was produced in North Korea.

4. The implications

We don’t have the report itself (yet) and aren’t in an ideal position to judge its accuracy (yet), so in place of a conclusion, let’s just cautiously advance a handful of observations.

First, other than some of the details of the engine design, and perhaps the aluminum alloy judged to be locally produced, nothing here comes as a huge surprise. For years now, publicly available reports from the U.S. intelligence community (here’s one) have contained statements like, “North Korea continues to pursue the development, production, and deployment of ballistic missiles with increasing range and sophistication. It continues to procure the needed raw materials and components from various foreign sources to support its missile industry.” That sort of assessment looks pretty good in light of the Unha-3 report, at least as it’s described here.

And really, why shouldn’t it look pretty good? Just where do you think Libya’s North Korean Scud-C missiles went?

Second, the findings reported yesterday nevertheless do come as a surprise to many people, including some very well-qualified non-governmental missile experts whom I hold in high esteem. As Josh warned a few years ago, there has been a tendency to underestimate what North Korea can do in the space and missile field, and possibly with technology in general.

At the root of these perceptions may be the close, personal encounter that many Western experts had with the Iraqi missile program in the 1990s and early 2000s through participation in UNSCOM or UNMOVIC. That’s an excellent qualification to engage in this type of analysis and certainly far beyond anything I can offer. But it also can be a distorting lens, if it leads to a presumption that North Korea in 2013 is no more capable than Iraq in 2003. Anyone who has subscribed to that view now faces the unhappy prospect of having to mark their beliefs to market. But there are worse things, if it comes to that.

Third, this seems as good a time as any to start considering the implications of the Unha-3 first stage for North Korea’s ability to design and build rocket engines.

Hopefully, it won’t be too long before we have the report itself.


  1. David (History)

    Wasn’t it General Zia who said “we will eat grass” to have nuclear weapons? He was right, Pakistan did get nuclear weapons and the population suffered. It seems quite similar in North Korea, with every picture of the Dear Leader showing him looking quite well fed and the generals who accompany him looking much shorter and malnourished.

    • SQ (History)

      That was Zulfiqar Ali Bhutto, but Zia surely agreed.

      KJI was sensitive about his height, which may have influenced who could stand next to him in photographs. I’m sure the generals all eat well. The corporals, maybe not.

  2. panterazero (History)

    I totally lack the background in contemporary international relations that would allow me to understand why the NKs do not deal directly with the Russians for some of this technology. Surely they could obtain hardware from the Russians that would be at least one generation ahead of anything available from Iran, Iraq, or any former Soviet clients. Would someone be kind enough to enlighten me?

    • SQ (History)

      The Russians participate in the MTCR.

    • John Schilling (History)

      Also, “The Russians” is ambiguous in this context. As SQ points out, the Government of the Russian Federation values the perception that it is a faithful player in the MTCR more than it values any cash payment the North Koreans can afford. The actual Russians who build missiles, who used to build missiles and are now driving taxicabs, who happen to have custody of warehouses full of old missile parts, some of those Russians appear to have been dealing directly with the Norks over the years.

      But that doesn’t give North Korea much choice regarding which bits of Russian technology they can buy. The part of the process where an eclectic assortment of old and somewhat incompatible missile parts and technologies get hammered together into a working missile, that’s all up to North Korea. And the uncertainty of such a supply chain is going to drive them towards telling such Russians as will deal with them, “Hey, guys, we’ll pay you real money to teach us how to build this stuff for ourselves” rather than simply “hey, sell us a bunch of those things over there”.

  3. rwendland (History)

    Maybe aluminum-magnesium alloy production is new, but there are reports the Soviet Union helped build NK’s first aluminium factory in Bukchang that began operations in 1982 or 1985. aka Pukchang/Buk Chang aluminium factory.

    Example reports are page 1090 of the North Korea Handbook (M.E. Sharpe, 2003) and at FAS:

    Mind you, the North Korea Handbook was published by the semi-official SK Yonhap, so may well be no more reliable than newspapers!

    • JFC Fuller (History)

      All aluminium is not equal.

  4. simorgh (History)

    Photos show the Unhas jet vanes quite clearly.
    Is it possible the first stage uses both Verniers and Jet Vanes?

    • SQ (History)

      Which parts are the jet vanes? I have a hard time reading it sideways.

  5. Anon2 (History)

    Three potential subjects for you to start a thread on:

    1) NK announcement of a third nuclear test.

    2) Albright’s analysis that says Iran can breakout in mid-2014.

    3) New intelligence of a nuclear weapons manufacturing facility at Khondab near Arak (suggesting Plutonium or additional hidden centrifuges).

    With regard to the Unha-3, it doesn’t at all surprise me that much of the missile has been made by the NK’s themselves. They are technically surprisingly advanced (like Iran), and so much talent could be put to good work at making a better life if they would stop wasting it on weapons of war. It is so sad to me.

    • Cthippo (History)

      “They are technically surprisingly advanced (like Iran), and so much talent could be put to good work at making a better life if they would stop wasting it on weapons of war. It is so sad to me.”

      While I agree with your point, I would say it doesn’t just apply to nations like North Korea and Iran. Just think what 10% of the US defense budget could do for improving education or veteran’s services or any of a myriad of other tings in this country.

  6. panterazero (History)

    ^^^^ Ahh, now I get it. Thank you all so much! I don’t suppose the NKs would dare pay off these “ambiguous Russians” with some of their high-grade phony hundred-dollar bills.

  7. Allen Thomson (History)

    > “The welding was not clean and the quality appeared as though it was made with a hammer, but despite the appearance, the technology was not coarse.”

    Sort of as aside, this is something one needs to be careful of. I once had an interesting conversation with someone who was involved in analyzing, IIRC, an SS-N-2 that the Soviets provided to a client and then, who knows how(*), found itself in the US. The guy said that, on first inspection, many of the parts looked really crude, but further study showed that they performed their jobs very well. Not pretty, but totally functional.

    (*) I suspect money played a part.

    • JFC Fuller (History)

      Pretty standard in soviet origin tech, the finish looks awful but it functions as it should. It reaches a point where 30% extra effort gains you 5% extra performance, the soviet logic being what’s the point if it does what they want it to.

  8. Peter Hayes (History)

    Hi Jeffrey, very interesting indeed.
    Question: the photo of the DPRK rocket engine vs the photo from Iran. The source link back to Geoffrey Forden says that the latter is likely Iranian produced. The photo he displays doesn’t particularly look like the NK rocket to me, or am I missing something? Geoffrey suggests that this is assimilated and regurgitated North Korean technology in Iran’s Phoenix program; but do we know what Nodong engine’s look like at this level of detail? Is Geoffrey speculating that this is a Nodong-derived rocket? If not, then the comparison with the DPRK engine is not only visually challenging; but may not relate closely or at at all to the Iranian engine.
    Observation: That said, now we are getting down to brass tacks re DPRK rocket technology and technique…or rather, to aluminum welds–not an easy technology to do in a “fine” rather than a “coarse” manner as any welder will tell you.
    Indeed, reference to “coarse” welding reminds me of visiting Wonsan Port many years ago. It was deserted. There was one lonely container with the door swinging open in the wind with a few zinc ingots in it and Havana Cuba stamped on the outside. And one small patrol boat tied up on the pier. As I reported at the time, it looked like it was made of flattened coca cans that had been welded together, except that the scraps of welded metal on the vessel were irregular. It reminded me of makeshift shelters in a refugee camp in Vietnam that I once visited during the war. The construction materials and technique didn’t mean that it didn’t float–it demonstrably was–or couldn’t operate at high speed, who knows, and that its guns would not be lethal–at least if they hit you.
    But it wasn’t impressive, looked improvised, and for anyone conversant with hull stresses at sea, one had to wonder about whether it was uniquely designed to spring serious leaks as there was no obvious way for this way of constructing the hull to receive and transmit forces from the motor, keel, and frames to and from the hull without stressing and flexing the welded joints in uneven manner.
    This makeshift engineering is typical of the DPRK’s engineering culture, and is the opposite of what is needed for reliable systems engineering, whether in the power sector, or in rocket systems with tens of thousands of parts. In effect, like their tractors, each of which is made and maintained now artisanally, each missile may be a unique work of art, a class in its own right, and its performance cannot be expected to prefigure the operating reliability of the next unit “off the line”–there is no line.

  9. Doug Richardson (History)

    Simorgh asked: “Is it possible the first stage uses both Verniers and Jet Vanes?

    Such a combination doesn’t make sense. If verniers are available, there seems no reason to accept the performance loss that vanes would impose.

    The blue-coloured features at the tail of the missile certainly look like part of a jet vane system, and both I and another presenter at a recent IHS-Jane’s webinar took this as evidence that the first stage used jet vanes.

    However, I’ve seen parts of the South Korean report, and in one diagram those blue features seem to be identified as being associated with a vernier motor.

  10. Tal Inbar (History)
  11. Hormuz P. Mama (History)

    There has been no mention so far of what rocket propellants were used. Were they storable or crogenic ? Storable would naturally make more sense, as a missile needs to be fired with a very low reaction time. Should that be the case, would it be nitrogen tetroxide oxidiser and unsymmetrical dimethyl hydrazine ? While, that workhorse propellant combination has been around for decades, it is still one of the most high-energy combinations available.I shall welcome opinions on these points.

    • John Schilling (History)

      The first stage is reported to have used nitric acid and kerosene, which almost certainly refers to the traditional Scud propellants of AK-27I (63% HNO3, 27% N2O4) and TM-185 (80% Kerosene, 20% Gasoline). This is an older propellant combination, not quite as high performance as NTO/UDMH but also not quite as obnoxious to handle and with a bit higher storage density. Not the best choice for a space launch vehicle (or an ICBM), but if you happen to have a bunch of engines that use it, it probably isn’t worth the bother of changing.

      We don’t have the upper stages to look at, but there is reason to believe that the North Koreans used NTO/UDMH for the third stage at least. The Iranian Safir launch vehicle used Isayev 4D10 vernier engines as the main propulsion for its upper stage, and those are NTO/UDMH engines; the Unha upper stage looks similar, the Norks and Iranians share a lot of liquid-rocket technology, and North Korea has displayed (but not launched) other rockets with an obvious Isayev propulsive heritage.

      And for the pedants, “NTO” means “Some Mixed Oxides of Nitrogen (MON) blend that is at least 70% Nitrogen Tetroxide, we don’t know the exact details”.

  12. A complete stranger (History)

    Im glad you highlighted to difficulty in getting some NGO analysts to accept the advanced capabilities of these countries. Some of us wasted a lot of time and effort trying to convince them they were wrong. I came to believe their stands were motivated more by their political beliefs–they didn’t want to admit any justication for missile defense–than scientific reasoning

    • Jeffrey (History)

      I like to think that most of the people I talk to simply see the evidence differently than I do, as hard as that is to accept sometimes.

    • a complete stranger (History)

      An interesting question to ask is “how long were they modelling the Iranian Safir as a Nodong with a scud on top (and some solid propellant “3rd stage” inside the clam shell) after the satellite was put in orbit?” And that was many months after Iran had shown details of the second stage. When shown videos of Iran machining engines for the second stage or brazing a Nodong engine together a common response was “they are trying to make us think they are capable of making their own engines.” When presented with evidence of the Safir’s last stage (the one in orbit together with the satellite) being much larger than the clam shell, some simply refused to consider the possibility. I would like to think they were simply viewing the evidence differently but…heck, thats what I told myself for a LONG time.

  13. Cthippo (History)

    In related news, South Korea finally took the blue pill and got their satellite up. Sources indicate it will broadcast “Gangham Style” 24-7 to the west which is better than whatever the North’s satellite was supposed to do.

    In other news, Iran launched a monkey into space atop one of it’s rockets and brought it back in one piece. I’m trying to work in an Ahmadinejad joke here, but failing.

    • Jeffrey (History)

      Let’s just say that, prior to the launch, aides were frantic to make sure Ahmadinejad and the monkey were both wearing the correct badges.

    • David (History)

      The Times of London’s front page claims that the launch and return of a monkey is a fake. See for yourself,