Jeffrey LewisOrigins of the Musudan IRBM

Over the years, I’ve been very interested in North Korea’s development of a new IRBM — called variously the SS-N-6 (US designation of a Soviet precursor system), the Musudan (US designation of the DPRK version) and the BM-25 (used in reference to kits allegedly exported from the DPRK to Iran), as well as a few other names.

The new IRBM is interesting because it represents a better base technology, in terms of more energetic propellants, than the Scud.  One of the big debates about the community of people interested in North Korea’s ballistic missile capabilities turns on the level of North Korean competence.  Do they do it themselves?  Do they have help?  How far can they stretch and stack what are basically Scuds?

And now, does this new technology open up new possibilities, like a three-stage road-mobile ICBM?

Some, like Robert Schmucker and Markus Schiller, are skeptical.  In our comments, Markus expressed his doubts:

[My] first impression by reading open source literature is either that the Musudan is based on the SS-N-6 because everybody knows that NK mastered SS-N-6 technology, or that NK mastered SS-N-6 technology because everybody knows that the Musudan is based on the SS-N-6. This is not a good starting point for further analysis. Remember: In assessments, it is way too easy for the author to confuse “we know” with “we think we know”!

As for me, I find this is a bit unfair — quite a lot of people, especially on this site, have spent plenty of time musing over whether the SS-N-6/BM-25/Musudan was just a paper missile or not. We’ve spent too much time trying to separate what “we know” from what
we think we know” to be accused of being confused. Wrong? Sure, it happens. Confused?  Not so much.

So let me recount what we know, and think we know, about the SS-N-6 aka Musudan aka BM-25.


Sheremetyevo Airport, October 1992

The prologue to this story is a strange incident at Sheremetyevo Airport in October 1992, where authorities stopped technical personnel, including some from the Makeyev rocket design bureau, from boarding a flight to North Korea. The incident was reported at the time in the Russian press.  There was some indication of state approval, at least at some level, as well as further stories about other groups of technicians. Dan Sneider provides the best write-up of which I know.

This is important because North Korea got its Scuds from Egypt, not the Soviet Union. Perhaps Makeyev was going to provide assistance to the North Koreans on Scuds — they didn’t manufacture the Scud but might be comfortable with the technology.  Or, perhaps, the North Koreans weren’t planning to settle for second-hand Scuds.


Mirim Airfield, DPRK, September 2003

In September 2003, Lee Chul-hee of JoongAng Ilbo cited a South Korean military intelligence official explaining that satellite images showed 5  launchers and 10 SS-N-6 like missiles at the Mirim airdrome. (Full text of the good bits is available at Total Wonkerr.)

Sonni Efron in the Los Angeles Times wrote a more detailed story at the same time:

There is no indication that the Russian government sanctioned the missile technology transfer or has had any involvement in North Korea’s missile program “in at least the last five years,” the official said.

“We’ve had hints of this for several years, but it’s only within the last year that we’ve been able to confirm that this did exist and it’s derived from Russian technology,” the official said, adding that the development “makes you wonder what else they might have been able to access” during that period.

This is the first indication of a new IRBM — a Makeyev-designed one, no less. Paul Kerr then followed up with his usual amazing work, getting a Department of State official to confirm that North Korea was “in the process of deploying” a new intermediate-range ballistic missile.

A month earlier, NASIC had released its Ballistic and Cruise Missile Threat slickee with nary a word about a new IRBM. In early 2004, however, after the stories in the JoongAng Ilbo and Los Angeles Times, DIA Director Lowell Jacoby referred to “press reports”  indicating North Korea was about to field a new IRBM based on the SS-N-6. My best guess was that Jacoby was hedging, and that the official talking to Efron was using a public leak to end internal debates about what the satellites saw at Mirim.

At this point, I would say that I was still a bit skeptical, to the say the least, about the SS-N-6 in North Korea.


Berlin, 2005

In 2005, the German newspaper Bild reported that North Korea sold Iran 18 SS-N-6 kits (“Irans Raketen reichen bald bis Berlin!) Bild is a tabloid, however, and the tone of the article did not do much to inspire confidence in the accuracy of the report. (I don’t normally take advice from the posters on Free Republic, but in this case one had some good advice: “Don’t click on the boobie pictures.”)

In July 2006, Gordon Fairclough at the Wall Street Journal cited US and Asian officials who seemed to confirm the BM-25 story, although the story was sourced to anonymous sources, none of whom provided a direct quote on the sale. (The direct quotes, on the contrary, expressed caution about the quality of US intelligence.)

Now, obviously, North Korea can’t transfer missiles it doesn’t have. But, over the same period the BM-25 story played out, the US intelligence community appeared to embrace the possibility of a new IRBM. In 2005, Jacoby confirmed that North Korea was developing a “new” IRBM.  In 2006, NASIC listed North Korea with less than 50 such missiles, although the document noted that the missile had not been flight-tested, a curious fact.

At this point, it seemed the US intelligence community had concluded that North Korea had such a missile. The lack of flight-testing, however, left me uncomfortable.


Pyongyang and Tabriz, Spring 2007

In April 2007, the Japanese Defense Ministry claimed the SS-N-6 appeared in a parade in Pyongyang, although Dan Pinkston couldn’t find the SS-N-6 in any of the video that the DPRK released of the event.

In May 2007, news reports suggested that Iran had test-fired one of the SS-N-6 missiles for North Korea. These reports cited South Korean and American intelligence reports and a “source” in Seoul. (As far as I can tell, the South Korean government actively leaks intelligence information to keep awareness of the North Korean threat at an appropriate level of panic.)

The outcome of these two events was that the DPRK version of the missile finally got a name — the Musudan.

It was in this period, by the way, that I managed to get involved in an unpleasant tangle with a guy who posted a picture of an SS-N-6 under the title “BM-25.”  Some of us took umbrage, as we were tracking the scant evidence for the Musudan very seriously — perhaps too seriously. The incorrect photo identification cost me half a day of work and I was sore about it.


Musudan-ri, 2009

In 2009, North Korea launched a rocket. Over the course of 2009 , Ted Postol and David Wright began arguing that the simplest model of the rocket used an SS-N-6 as a second stage. [Update: 22 May 2013 David now believes this to be incorrect, based on images of debris recovered from the December 2013 Unha launch.]

Postol also concluded, based on photographs that Iran released, that the second stage of Iran’s Safir missile was based on the vernier engines of the SS-N-6.

Those two revelations seemed to lend support to the story in Bild. We did not know it at the time, but the US also distributed a pair of MTCR-related cables in 2009 that made clear the view of the IC: North Korea had developed a new IRBM, called the Musudan, based on the SS-N-6 and exported it to Iran:

Recently, North Korea has developed a new land-mobile IRBM –called the Musudan by the United States. The Musudan is a single-stage missile and may have a range of up to 4,000 km with a 500 kg payload. The Musudan is derived from the SS-N-6 submarine-launched ballistic missile (SLBM) and represents a substantial advance in North Korea’s liquid propellant technology, as the SS-N-6 had a much more advanced engine and used more energetic propellants — unsymmetrical dimethylhydrazine (UDMH) and nitrogen tetroxide (N204) — than those used in Scud-type missiles. Development of the Musudan with this more advanced propulsion technology allows North Korea to build even longer-range missiles — or shorter range missiles with greater payload capacity — than would be possible using Scud-type technology.

Furthermore, the second-stage of the Safir utilizes steering engines that are almost certainly derived from the Soviet-era SS-N-6 (Soviet designation: R-27 or RSM- 25) submarine-launched ballistic missile. Iran could have acquired this technology from North Korea’s probable transfer of the BM-25 MRBM, which is a variant of Pyongyang’s SS-N-6- derived Musudan IRBM. In addition to the successful staging of these two main boosters, it is likely that Iran made progress with the use of high performance hypergolic (self-igniting) propellants in the SS-N-6-derived second stage. The adaptation of this propellant technology to missile systems could significantly enhance Tehran’s ability to develop a new generation of more-advanced ballistic missiles.

Now, the US intelligence community can make mistakes. But it is interesting to know what they think and, more importantly, why.


Pyongyang, 2010

In 2010, the DPRK paraded (again?) the Musudan down the streets of Pyongyang — and this time released the pictures to prove it. The missile was a little bigger than the SS-N-6, suggesting that North Korea had enlarged it, much as it transformed the Scud into the Nodong.


Tongchang-dong, March 2012

In March 2012, when North Korea released pictures of the Unha-3 and announced splashdown zones, again the simplest explanation was that the missile had an SS-N-6 second stage and a third-stage with SS-N-6 vernier engines (like the second stage of the Safir).

That missile went right into the drink.

In April, AFP cited an “intelligence source” claiming that the DPRK carried out four static engine tests for the new ICBM over a 16 week period earlier this year.  That followed a similar report in November 2011, which suggests the sixteen-week period might have run from November 2011-February 2012.


At this point, we are pretty sure that North Korea has access to SS-N-6 technology. We know that Makeyev people probably traveled to North Korea and it seems that some of the technology has made it into North Korean and Iranian space launch vehicles.

Moreover, North Korea has paraded a missile — perhaps mock-up — through the streets of Pyongyang either once or twice.

All that is missing is a flight test. Of course, there are rumors that Iran tested the missile for North Korea. And there are also the reports that North Korea conducted static engine tests from November 2011-February 2012. The US intelligence community thinks the missile is deployed, possibly on the basis of tests in either Iran or North Korea.  Or perhaps they are just covering their rears.

It is possible, I suppose, that North Korea has a limited number of SS-N-6 kits that were cannibalized for a couple of showy Iranian and North Korean space launches, leaving nothing but spares for a few dummy missiles to scare the hell out of the foreigners. But that doesn’t, to me at least, seem like the simplest explanation. It is, I think, at least as plausible, that the North Koreans have lots of kits and some ability to crank out crappy copies of the SS-N-6 in various shapes and sizes — which for their purposes may be good enough.

Or, as Marshall Nie Rongzhen used to say, better than rifles and millet.


  1. Pavel (History)

    It’s “Makeyev”. Also, BM-25 was discussed in some detail during the U.S.-Russian missile threat talks in 2009 (Wikileaks:

    • Jeffrey (History)

      I’ve fixed the transliteration error. Thank you for the additional link.

  2. Alan Tomlinson (History)

    It’s a minor point, but Bild, is not a magazine but a newspaper. It is quite right-wing and has a similar relationship to factual reporting that the Warner Brothers cartoons have to physics. Some things are true, but that’s often incidental and the dedication to truth-telling is pretty much non-existent.


    Alan Tomlinson

    • Jeffrey (History)

      Danke schoen. I’ve fixed the error.

  3. James (History)

    I wanted to ask, how different are the Iranian space launch vehicles to the North Korean’s in a technical way?

    Excluding the fact that Iran seems to be having success in putting satellites in orbit where as the NK don’t.

  4. Harry (History)

    Dear Jeffrey,

    What are you hoping to hear? This looks to me like a fishing trip.

    To my opinion, the central question is:

    Do the NORKS have mastered the SS-N-6 technology?

    Regarding the very specific purpose of the SS-N-6, ie the capability to have an ICBM in the limited space of a nuclear submarine, it would be a gross error to port the same technology to a missile which does not have this size/space limitations. As such, there seems to be no incentive to master the SS-N-6 technology, with its submersed main engine in the fuel tank.

    Which in the end, would support the excellent analysis of Schiller et al.


    • russiannavyblog (History)

      I agree with the basic premise of your post about overengineering the missile, however according to this link that I can’t really vouch for, the SS-N-6 had it’s origins in a ground mobile version of the SS-N-4. The road mobile version was cancelled and the program picked up in the early 60s as the SS-N-6.

    • John Schilling (History)

      Beggers can’t be choosers. If North Korea wants to go much beyond the Nodong, they need a more efficient engine. If they can’t develop such a thing from scratch, and they can’t buy it openly on account of sanctions and general isolation, they are limited to what they can buy (both in terms of hardware and technical assistance) on the black market.

      I do not believe there are all that many high-performance ballistic missile engines available on the black market. If, once upon a time, some Russian general experimenting with this newfangled “capitalism” thing offered the Norks a bunch of surplus SS-N-6 missiles and mercenary technicians to help get them running, that right there would be a reason for the North Koreans to master SS-N-6 technology and make it fit whatever particular operational requirements they have.

  5. joshua (History)

    Jeff, thanks for this careful review of the bidding. It’s a juicy topic, isn’t it?

    Just one small quibble. Including 2007, there have now been _three_ parades of the Musudan, the last being this past April 15.

    Other odds and ends:

    1. The appearance in 2003 at Mirim Airfield before a parade seems to be connected to the replica of Kim Il Sung Square built there, described recently by NK Econ Watch:

    2. After the 2010 parade, experts quoted by the _Washington Post_ judged the items displayed on TELs to have been mockups:

    3. Even more alternative designations for the Soviet SS-N-6 SLBM are listed in the table here:

  6. John Hallam (History)

    What are the chances of its working for more than 30 secs? The operational record is not good.

    John Hallam

  7. George William Herbert (History)

    Further this, Iran is now apparently making 4D10 verniers, having publicized fabrication in progress photos.

    If the tech came via NK then it would seem unlikely NK can’t also fab those.

    It’s possible but to me unlikely / implausible that they would go for that effort without also making the vernier pumps package, though I don’t recall photos of that.

    The main engine could well be another story.

    There was a large rotary vacuum brazing chamber demonstrated in Iran that I believe fits a 4D10 main thrust chamber. But we can’t jump from that to assuming it’s for that engine.

    It’s taking forever nut I am slowly working on the SS-N-6 structure and Musudan structural implications. I would love if it turned out someone in the west had acquired a R-27 and could let me inspect it, but I can bound the problem based on what I already have.

    • Murray Anderson (History)

      Iran has a large automobile production industry, so they have plenty of production engineers and an experienced workforce, even if their designs are still largely derivative. North Korea has nothing like this, so it’s quite possible that Iran has capabilities that North Korea lacks.

    • John Schilling (History)

      Engineers are not a fungible commodity, no matter how much simpler that would make project management. There is a great deal of specialized knowledge involved, not just between fields but unique to each product line. And too much of it never quite gets written into the blueprints and manuals.

      So, while North Korea has fewer engineers than Iran, they probably do have more liquid rocket propulsion engineers, and they seem to have had actual Isayev engineers as consultants during the evolution of this system. If Iran has essentially stock Isayev 4D10s working on an operational space launch system, that is far more credibly the result of a Russia -> North Korea -> Iran technology transfer than e.g. tossing a crate of old 4D10s at a bunch of automotive engineers and saying “make it work!”

      Which is not to say that automotive engineers can’t make working rockets, even very good ones. But the odds are somewhat against them, and the results won’t be a stock Isayev 4D10 even if that is the hardware they start with.

  8. Markus Schiller (History)

    Jeffrey: Great compilation of all relevant Musudan information.

    Please allow two remarks that should be considered:

    – Makeev was/is a rocket design bureau. The engines of the R-27/SS-N-6, and of plenty other Makeev missiles, were designed by the Isaev design bureau. (Years ago, we opted for this transliteration instead of Makeyev and Isayev and used it since then. Sorry, old habits die hard.) Makeev people are not the engine experts – Isaev people are.

    – In paragraph 1, a story of the JoongAng Ilbo in 2003 is mentioned (and linked via Total Wonkerr). In this story, the following is stated:
    “Intelligence officials in Japan, South Korea and the United States have inferred from the unique shape of the missile’s warhead – which resembles the top of a baby bottle – that the North’s version was developed based on the Soviet-designed, submarine-launched SS-N-6.”
    If this was the only reason to postulate a SS-N-6 relation at that time, then it was based on very poor evidence. Especially since the warheads of the Musudan that were later displayed on parades look somewhat different than SS-N-6 warheads.
    Also, all warheads for the SS-N-6 were nuclear, and the missiles were only mated with the warhead shortly before they were moved into the submarine launch tubes. It is therefore highly unlikely that NK received original Soviet warheads. If the Musudan really is deployed in significant numbers for some years now (as stated in paragraph 2, ”In 2006, NASIC listed North Korea with less than 50 such missiles”), the warhead has to be conventional. In that case, NK modeled their conventional warheads after the shape of the nuclear SS-N-6 warheads when they had no design restrictions at all.
    As you see, there are several aspects that do not quite match.

    It is good to see this discussion going on. No matter what the result will be, it is definitely important to shed some more light on the NK missile situation.

    Markus & Robert

    • Jeffrey (History)

      1. The original detention at Sheremetyevo included personnel from Isayev as well. I omitted that detail, largely because I have not been able to find the interview that something called “Moscow News” did with two missile specialists named Yuriy Besarabov and Vladimir Yusachev, “both of whom were among the Russian specialists who tried to emigrate to North Korea to work on the missile program there.” The story states, apparently, that “Besarabov and Yusachev state that the original contacts to the specialists were made through their places of employment, the Isayev and Makayev design bureaus, and that Russian scientists who are currently in North Korea may have left Russia with official permission.”

      2. On the issue of design provenance, I noted that South Korea has a practice of leaking intelligence information that is embarrassing to North Korea. Leaks are stylized forms of political communication that are not intended to persuade engineers. They must be read with some awareness of the motive of both the source and the reporter. Neither the person designated to leak the information nor the reporter are likely to be technically-astute. Nor would Joongang Ilbo’s readers care to be treated to a discussion of the the cable ducts or other features. My best guess is that the “baby bottle nose” was simply the easiest detail to convey to a general reader, not the only one available to the intelligence community. Note what the “U.S. official” told Sonni Efron: “We’ve had hints of this for several years, but it’s only within the last year that we’ve been able to confirm that this did exist …” Those “hints” presumably extend beyond the baby bottle nose, perhaps to Russian specialists with big mouths or drinking problems. For the general reader, however, the similarity between this and this will be judged sufficient. From a satellite image, by the way, they may be indistinguishable.