Jeffrey LewisSlebos Bottom Bearing Preforms

(A Swiss-made Bottom Bearing from Iraq similar to the Dutch model discussed below.)

Bet you’re all hot and bothered now. Along with “portal perimeter monitoring”, “bottom bearing preform” just sounds naughty.

Mark Hibbs is following an obscure Dutch export control case that has been virtually ignored by the US press. Henk Slebos was convicted of illegally exporting a variety of dual-use items to Pakistan, for use in their nuclear weapons program.

The charge on which he was acquitted, however, is the interesting one. Hibbs reports that, in 2001, Slebos sent 10,000 bottom bearing preforms (an important component of a centrifuge) to the Institute for Industrial Automation in Rawalpindi:

The Alkmaar court then and since did not divulge that Slebos had in 2001 also shipped thousands of other steel bearing balls to IIA that precisely matched the metallurgical and design specifications for the bottom bearing of the Urenco centrifuge known as CNOR. Intelligence sources told NuclearFuel that evidence that Slebos exported these goods to Pakistan was considerable.

Western officials said that Pakistan had given up on CNOR by around 1985 in favor of another Urenco-design machine, G-2. It was strongly believed that when Slebos exported these items to IIA, in 2001, they were destined for use in so-called P-1 centrifuges. These centrifuges, based on CNOR, were to be set up with Khan’s assistance in Iran, Libya, and perhaps North Korea, the sources said.

Slebos was acquitted because the Dutch government failed to promptly inform him that the sale was prohibited by a Dutch catch-all clause. Slebos does not, apparently, dispute the facts of the export.

The fact that the bearing preforms matched the CNOR centrifuge is interesting because it means they were for re-export, likely to Libya or Iran.

Hibbs previously reported (more) that the CNOR formed the design basis (along with the SNOR design) for the P-1 centrifuges at Natanz. Joby Warrick and Glenn Kessler reported that the design of the centrifuges had been substantially modified—so the technical details are murky.

I wonder … For how many preforms, at present, can we account?


  1. Muskrat (History)

    Obreptitious means, according to google,

    “Done or
    obtained by surprise; with secrecy, or by concealment of the truth”

    That’s a pretty snarky acronym then—“the rotor we stole.” Who says proliferators can’t have a sense of humor? Or is that some Western title slapped on by analysts?

  2. Jeffrey Lewis (History)

    That is interesting, isn’t it? That bears some looking into …

  3. Stephanie Lieggi (History)

    Thanks for pointing out Mark Hibb’s new article on the notorious Mr Slebos. This case has not received nearly enough attention here, considering it is pretty clear that the assistance Slebos gave to Khan was critical for Pakistan’s nuclear program and likely ultimately for Khan’s ability to assist other programs.

    For those of you who are Dutch speakers, there is a very interesting (albeit creepy) interview with Slebos on the Dutch TV program Zembla from November 2005. The extent to which this guy is proud of his activities is just irritating. It makes the fact that he only got about four months in jail (one year with eight months suspended) and a Euro100,000 fine disturbing.

    If you look at the court documents (which of course also requires you to speak Dutch) there is an interesting issue that comes out—that much of the evidence that was collected in a search of Slebos’s offices was ruled inadmissable since there were Dutch intelligence agents present and actively participating—which was a problem since it was not stipulated in the search warrant. Whether this would have impacted the ruling on the bottom bearing preforms transfer is unclear.

  4. Theresa Hitchens (History)

    Mr. Hibbs’ past work uncovering nuclar proliferation, including the AQ Khan network, is praised, and recounted, in a really scary article in this month’s Atlantic by William Langewiesche. I recommend reading it.

  5. Jeffrey Lewis (History)

    Other sources suggest SNOR and CNOR stand for Scientific Nuclear Orbital Rotor and Cultivated Nuclear Orbital Rotor.

  6. Frank Slijper (History)

    To add to Stephanie’s comment: the preforms surely weren’t part of the indictment. I guess the authorities only discovered this when the preforms were already exported. Apparently the preforms don’t require an export licence here. Only a catch-all clause could have stopped the export, but of course only when it was issued before the stuff was leaving the country. So it looks more like another intel failure in monitoring and acting on Slebos’ activities.
    As there isn’t that much available on Slebos in English, some of you may find it interesting to read this article I wrote on Slebos’ conviction in the Nuclear Monitor ( Also there is more to find on him and other Dutch suppliers in the 1st 2 chapters of the Greenpeace International report that was released at the NPT prepcon in 2004 (

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