On 7 September 1997, the CBS newsmagazine Sixty Minutes broadcast an alarming story in which former Russian National Security Adviser Aleksandr Lebed claimed that the Russian military had lost track of more than 100 suitcase-sized nuclear bombs, any one of which could kill up to 100,000 people.

"I'm saying that more than a hundred weapons out of the supposed number of 250 are not under the control of the armed forces of Russia," Lebed said in the interview. "I don't know their location. I don't know whether they have been destroyed or whether they are stored or whether they've been sold or stolen, I don't know."

Asked if it were possible that the authorities did know where all the weapons were and simply did not want to tell Lebed, he said, "No."

Last May Lebed said at a private briefing to a delegation of U.S. congressmen that he believed 84 of the one-kiloton bombs were unnaccounted for. In the interview with 60 Minutes, conducted in late August, Lebed said he now believes the figure to be more than 100.

Lebed stated that these devices were made to look like suitcases, and could be detonated by one person within half an hour. According to Lebed, he learned of the existence of these weapons developed for special operations only a few years ago. While national security adviser to Yeltsin he commissioned a study to report on the whereabouts of these devices. Lebed was fired as national security adviser Oct. 17, 1996 amid intense political jostling while President Boris Yeltsin was awaiting heart surgery. He admits that he had only preliminary results of his investigation at that time, and these results are the basis of his current claims.

The bombs, measuring 60 x 40 x 20 centimeters (24 x 16 x 8 inches), had been distributed among special Soviet army intelligence units (GRU), Lebed said.

The offical response of the u.S. government was given by State Department spokesman James Foley on 5 September (based on CBS' pre-release of the interview transcript).

"The government of Russia has assured (us) that it retains adequate command and control of its nuclear arsenal and that appropriate physical security arrangements exist for these weapons and facilities."

"We have been assured by the Russian authorities that there is no cause for concern. We believe the assurances we have received," Foley said.

Russia's atomic energy ministry further rejected Lebed's claims on September 10.

"We don't know what General Lebed is talking about. No such weapons exist," a ministry spokesman told AFP. "Perhaps he meant old Soviet nuclear artillery shells, which are all being safely guarded."

Interfax news agency quoted a ministry statement as saying Russia's nuclear security system "keeps nuclear warheads under tight control and makes any unauthorised transportation of them impossible."

Lebed has been warning of poor security over nuclear weapons in Russia since at least late last year, when he met with Republican Sen. Richard Lugar of Indiana (28 Nov 1996). At the time Lebed had called controls over nuclear material in the former Soviet Union "unsatisfactory," making Russia vulnerable at nuclear plants and facilities. Lugar and Georgia Democrat Sam Nunn sponsored a law in 1991 that provides American technical aid to Russia to eliminate nuclear warheads made redundant by arms control pacts, and account for and control nuclear material.

Questions about Lebed's credibility were immediately raised. Abruptly cast out of power, presumably leving him with grudges, he is likely to be a leading contender in the next presidential election. In elections in June 1996 he placed third, behind Yeltsin.

State Department spokesman Foley said Lebed's allegations carried "not a lot of credibility."

He said US officials have often raised the matter of nuclear security with their Russian counterparts and that "we've been assured by the Russian authorities that there's no cause for concern."

Another stream of criticism about the Sixty Minutes report was directed at the producers of the story. A good account of this is given (perhaps surprisingly) in the Sept. 27 - Oct. 3 issue of TV Guide (pg. 49). Basically, the producer of the story, Leslie Cockburn, is currently promoting a book she co-wrote with her husband Andrew on the dangers of nuclear terrorism called One Point Safe. In addition the Cockburns are co-producers of the new, just released, Dreamworks SKG film The Peacemaker. The star commentator of the Sixty Minutes report, ex-National Security Council staffer Jessica Stern, was a paid consultant to The Peacemaker, and alleged was the model for the character played by Nicole Kidman. Stern is also working on her own book on nuclear terrorism.

While the interlocking self-interests involving the various participants in the preparation of the Sixty Minutes report certainly do not prove any disingenuousness on the part of any of them, it does nothing to bolster the credibility of the claims.

By Carey Sublette, compiled from news service releases, the Washington Post, the Los Angeles Times, the Sixty Minutes program, and (yes) TV Guide.
 

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Commentary
It is difficult to evaluate the credibility of Lebed's assertions. On one hand a great deal of material has appeared in recent years reporting or documenting problems with the post-Soviet control of nuclear weapons and weapons usable fissile material. On the other, that such a specialized and dangerous device that was explicitly under the control of the GRU, one of the most disciplined of Soviet military organizations, should vanish in large numbers seems incredible.

Lebed has had very important and influential positions which could give him access to detailed information on nuclear weapons. But his current position -- outside of the government, maneuvering for political advantage -- does not inspire much confidence that the information he provides is unbiased and accurate.

But, as has been often pointed out, given the great destructiveness of nuclear weapons, even a very low probability risk is cause for great concern.

It is a good bit easier to provide a analysis of the likely characteristics of the weapons Lebed describes. See Section 4.2 of the Nuclear Weapons FAQ for more details.

A suitcase bomb with dimensions of 60 x 40 x 20 centimeters is by any standard a very compact nuclear weapon. Information is of course lacking on compact Soviet weapons, but fair amount of information is available on compact U.S. designs which provides a good basis for comparison.

The smallest possible bomb-like object would be a single critical mass of plutonium (or U-233) at maximum density under normal conditions. An unreflected spherical alpha-phase critical mass of Pu-239 weighs 10.5 kg and is 10.1 cm across.

A single critical mass cannot cause an explosion however since it does not cause fission multiplication, somewhat more than a critical mass is required for that. But it does not take much more than a single critical mass to cause signifcant explosions. As little as 10% more (1.1 critical masses) can produce explosions of 10-20 tons. This low yield seems trivial compared to weapons with yields in the kilotons or megatons, but it is actually far more dangerous than conventional explosives of equivalent yield due to the intense radiation emitted. A 20 ton fission explosion, for example, produces a very dangerous 500 rem radiation exposure at 400 meters from burst point, and a 100% lethal 1350 rem exposure at 300 meters. A yield of 10-20 tons is also equal to the yield of the lowest yield nuclear warhead ever deployed by the U.S. -- the W-54 used in the Davy Crockett recoilless rifle.

A mere 1.2 critical masses can produce explosive yield of 100 tons, and 1.35 critical masses can reach 250 tons. At this point a nation with sophisticated weapons technology can employ fusion boosting to raise the yield well into the kiloton range without requiring additional fissile material.

Now the amount of fissile material that constitutes a "critical mass" varies with the material density and the type of neutron reflector present (if any). A high explosive implosion can compress fissile material to greater than normal density, thus reducing the critical mass. A neutron reflector reduces neutron loss and reduces the critical mass at a constant density. However generally speaking, adding explosives or neutron reflectors to a core adds considerably more mass to the whole system than it saves.

A limited exception to this is that a thin beryllium reflector (thickness no more than the core radius) can actually reduce the total mass of the system, although it increases its overall diameter. For beryllium thicknesses of a few centimeters, the radius of a plutonium core is reduced by 40-60% of the reflector thickness. Since the density difference between these materials is on the order of 10:1, substantial mass savings (a couple of kilograms) can be achieved. At some point though increasing the thickness of the reflector begins to add more mass than it saves (since volume increases with the cube of the radius), this marks the point of minimum total mass for the reflector/core system.

A low yield minimum mass or volume weapon would thus use an efficient fissile material (plutonium or U-233), a limited amount of high explosives (sufficient only to assembly the core, not to compress it), and a thin beryllium reflector.

We can now try to estimated the absolute minimum possible mass for a bomb with a significant yield. Since the critical mass for alpha-phase plutonium is 10.5 kg, and an additional 20-30% of mass is needed to make a significant explosion, this implies 13 kg or so. A thin beryllium reflector can reduce this by a couple of kilograms, but the necessary high explosive, packaging, triggering system, etc. will add mass, so the true absolute minimum probably lies in the range of 10-15 kg (probably closer to 15 than 10).

This is probably a fair description of the W-54 warhead. This was the lightest warhead ever deployed by the U.S., with a minimum mass of about 23 kg and had yields ranging from 10 tons up to 1 Kt in various versions. The warhead was basically egg-shaped with the minor axis of 27.3 cm and a major axis of 40 cm. The test devices for this design fired in Hardtack Phase II (shots Hamilton and Humboldt on 15 October and 29 October 1958) weighed only 16 kg, impressively close to the minimum mass estimated above. These devices were 28 cm by 30 cm.

W-54 Davy Crockett (38 K)

The W-54 probably represents a near minimum size for a spherical implosion device (the U.S. has conducted tests of a 25.4 cm implosion system however).

The W-54 is certainly light enough by itself to be used in a "suit case bomb" but the closest equivalent to such a device that U.S. has ever deployed was a man-carried version called the Mk-54 SADM (Small Atomic Demolition Munition). This used a version of the W-54, but the whole package was much larger and heavier. It was a cylinder 40 cm by 60 cm, and weighed 68 kg (the actual warhead portion weighed only 27 kg). Although the Mk-54 SADM has itself been called a "suitcase bomb" it is more like a "steamer trunk" bomb, especially considering its weight.

To fit a nuclear device in a suit case only 20 cm wide (as Lebed specified) would require a design that was somewhat slimmer than the W-54. Warheads fitting this description have been developed. They employ "linear implosion" technology and are used in small diameter atomic artillery shells.

The linear implosion concept is that an elongated (football shaped) subcritical mass of material can be deformed into a critical spherical configuration by embedding it in a cylinder of explosives which are initiated at each end. As the detonation progresses from each direction towards the middle, the fissile mass is squeezed into a supercritical shape.
 
 

This approach probably produces devices requiring more fissile material and greater amounts of high explosive, but the diameter can be reduced compared to spherical implosion designs. The U.S. has used this approach to make 203 mm (8 inch) and 155 mm (6.1 inch) artillery shells, and it is reported that designs as small as 105 mm (4.1 inches) are possible. It is quite likely, that should the suitcase bombs described by Lebed actually exist, that they would use this technology.

By Carey Sublette
 
 

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MILNET Analysis
Looking over Carey's analysis, it is clear that a suitcase weapon is not only possible, it is probable given the material availability. A terrorist need only get their hands on the appropriate critical mass (as was done in the movie Peacemaker), and they are on their way.
We only wonder about the long term viability of such weapons. If they were manufactured in the late 70s for instance, they may have needed to be refurbished in order to remain effective. They would still be quite dangerous in terms of latent toxicity and radioactive emissions, however, would they retain their ability to sustain critical mass? There are hints that the early radioactive cores, left untouched, degrade in purity to a point that in some number of years, they are no longer viable as nuclear weapons. If this IS the case, then the Soviet suitcase weapons, unless refurbished, have long ago ceased to be a threat.

We consulted with Carey about this effect and in his opinion, it would be so easy to design a compensating mechanism that refurbishment does not seem to be that big an issue in terms of yield or effectiveness. A slight amount of Americium (an element created by the decay) contamination of cores might exist, but it tends to stabilize the Plutonium rather than seriously impact its explosive power. Release of helium would be a more critical problem, yet that too is such minor quantities that it really matters little. In his opinion, the viability of any nuclear weapon is not effected negatively by decay or contamination of the core material even in periods of decades, however, that refurbishment by the nuclear poweres probably does include reprocessing core material to remove Americium.

From what he has said, though, this sounds like the refurbishment and removal of this material is more of a case of being perfectionists rather than trying to offset any appreciable loss in yield. He did say however, that the effects of aging on nuclear weapons may produce problems in terms of stockpiling. From his explanation, we might draw the conclusion that nuclear weapons must be inspected and refurbished in order to prevent them from accumulating radioactive helium gas or other toxic gases that would make storage and retrieval of weapons dangerous. All of which mean nothing in terms of a terrorist's use of the weapons.
 
 

MILNET Nuclear Weapons
 
 

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