By Carey Sublette
Last changed 10 October 2001
As is recounted below nuclear weapons that can fit in a very heavy, but normal-sized suitcase or briefcase are a real possibility. Devices of the necessary compact size have actually been built and tested.
It has been alleged that weapons were actually manufactured by the former Soviet Union for use by its intelligence services that packaged compact kiloton range bombs in ordinary looking suitcases, and that a considerable number of these have gone missing -- perhaps through simple inventory accounting shortcomings, but perhaps not.
The possibility that these devices may have been stolen and sold to terrorist groups is nearly anyone's worst nightmare, especially after 11 September 2001. A story in the 25 October 1999 issue of the Jerusalem Report (quoted in Bin Laden has several Nuclear Suitcases) asserted that Osama bin Laden's terrorist organization al Qaeda has acquired a number of these devices in exchange for a "$30 million in cash and two tons of Afghan heroin". The source of this allegation Yossef Bodansky is apparently a free-lance analyst with connections to Israeli intelligence and conservative Republican think tanks. Bodansky's source for this information is unknown, as its reliability. [NB: In evaluating this claim it would be well to recall that Libya has reportedly offered over a billion dollars for a single nuclear weapon, but appears to have been unsuccessful in obtaining one; and that Russia has been the victim of terror bombings killing hundreds of civilians in recent years with the suspicion of responsibility pointing at muslim groups allied with bin Laden. Such devices in the hands of Islamic terrorist groups would be the greatest threat to Russia's security today, and it would go to almost any length to prevent it.]
The most detailed and persuasive account of Osama bin Laden's interest (if not capability) in nuclear weapons is provided by the testimony of Jamal Ahmad al-Fadl, a native of Sudan and ex-bin Laden associate, in the trial of the earlier World Trade Center bombing: United States of America v. Usama bin Laden, et al. (S(7) 98 Cr. 1023) prosecuted February-July 2001 in United States District Court (transcripts are on-line at http://cryptome.org/usa-v-ubl-dt.htm ).
At the trial al-Fadl recounted in detail his extensive but unsuccessful efforts to obtain enriched uranium for al Qaeda through contacts in Khartoum, Sudan during 1993-94 and afterward. At one point a fee of $1.5 million was discussed, and plans were made to test uranium samples to see if they could be used to build a bomb (this testimony was delivered mostly during Day 3 and Day 4 of the trial.
It has been 27 years now since John McPhee's The Curve of Binding Energy brought it to public attention that with sufficient fissile material - highly enriched uranium or plutonium - there are no substantial technical obstacles for a small group to manufacture a simple but highly destructive nuclear bomb.
The US itself demonstrated in the Nth Country Experiment that the technical barrier to designing a nuclear device is quite low. This study is detailed in the classified report UCRL-50248, "Summary Report of the NTH Country Experiment," W. J. Frank, ed., March 1967, but a declassified version of it is on-line at the National Security Archive. The experiment was conducted to see how much effort was actually required to develop a viable fission weapon design starting from nothing. Three newly graduated physics students were given the task of developing a detailed weapon design using only public domain information. The project reached a successful conclusion, that is, they did develop a viable design after expending only three man-years of effort over two and a half calendar years. In the years since, much more information has entered the public domain so that the level of effort required has obviously dropped further.
There is no doubt that if a group like al Qaeda were to obtain sufficient fissile material - no more than 12 kg of plutonium, or 50 kg of highly enriched uranium, and quite possibly less, a highly destructive bomb could be constructed. It is very doubtful that a simple nuclear device developed by a small group could qualify as a "suitcase bomb", but most any ordinary vehicle would suffice for transportation.
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."
During May 1997 Lebed said at a private briefing to a delegation of U.S. congressmen that he believed 84 of the one-kiloton bombs were unaccounted for. In the interview with 60 Minutes, conducted in late August, Lebed said he now believed 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 before. 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 17 October 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 subsequent claims.
The bombs, measuring 60 x 40 x 20 centimeters (24 x 16 x 8 inches), had been distributed among special Soviet military intelligence units belonging to the GRU, Lebed said.
The official response of the US 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,
Russia's atomic energy ministry further rejected Lebed's claims on 10 September.
"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 unauthorized transportation of them impossible."
Lebed has been warning of poor security over nuclear weapons in Russia since at least late 1996, when he met with Republican Sen. Richard Lugar of Indiana (28 November 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 leaving 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 was given (perhaps surprisingly) in the Sept. 27 - Oct. 3 issue of TV Guide (pg. 49). Basically, the producer of the story, Leslie Cockburn, was 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 was 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.
Lebed later testified before the Congressional Military Research and Development Subcommittee at a hearing on 1 October 1997 where he stated that the bombs were made to look like suitcases and could be detonated by one person with less than 30-minutes preparation. Lebed's claim that such devices had been manufactured were corroborated on 3 October by testimony from Russian scientist Alexei Yablokov, former environmental advisor to President Yeltsin while serving on the Russian National Security Council (see www.house.gov/curtweldon/pr_100397.htm). According to the press release from Rep. Curt Weldon's office (R-Pa):
Yablokov stated that he personally knows individuals who produced these suitcase-size nuclear devices under orders from the KGB in the 1970s specifically for terrorist purposes. As a result of their being produced for the KGB, Yablokov has stated that they may not have been taken into account in the Soviet general nuclear arsenal and may not be under the control of the Russian Defense Ministry.For Yablokov's comments on suitcase nukes and Lebed given on WGBH/Frontline see http://www.pbs.org/wgbh/pages/frontline/shows/russia/suitcase/comments.html.
Weldon has further said that the Russian government eventually acknowledged that such weapons had been produced.
In a later floor speech (Security Issues Relating to Russia, 28 October 1999) Weldon asserted that a total of 132 devices had been built with yields from 1 to 10 kilotons, and that 48 were unaccounted for.
Compiled from the House of Representatives on-line archive, news service releases, the Washington Post, the Los Angeles Times, the Sixty Minutes program, and (yes) TV Guide.
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 a fair amount of information is available on compact US 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 significant 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 US -- 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.
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 (and is 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 US, with a minimum mass of about 23 kg (it also came in heavier packages) 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 US 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 "suitcase bomb" but the closest equivalent to such a device that US 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.
Minimum mass and minimum volume are not the only design criteria of interest of course, since even 25.4 cm (10 inches) is rather thick even for a suitcase. Another approach is to develop a minimum diameter or minimum thickness design.
Minimizing nuclear weapon diameters has been a subject of intense interest for developing nuclear artillery shells, since the largest field artillery is typically the 208 mm (8.2 inch) caliber, with 155 mm (6.1 inches) artillery being the workhorse. Nuclear artillery shell designs with diameters as small as 105 mm have been studied. Packaging a nuclear artillery shell in a suitcase is an obvious route for creating a compact man-portable device.
The US has developed several nuclear artillery shells in the 155 mm caliber. The only one to be deployed was the W-48 nuclear warhead developed by UCRL, packaged in the M-45 AFAP (artillery fired atomic projectile) shell. The W-48 nuclear warhead measured 86 cm (34") long and weighed 53.5-58 kg (118-128 lbs). Its yield was on the order of 70 to 100 tons (it was tested in the Hardtack II Tamalpais shot with a yield of 72 tons, predicted yield was 100-300 tons).
The smallest diameter US test device publicly known was the UCRL Swift device fired in the Redwing Yuma shot on 28 May 1956 . It had a 5" (12.7 cm) diameter, a length of 62.2 cm (24.5 inches) and weighed 43.5 kg (96 lb). The test had a yield of 190 tons, but was intended to be fusion boosted (and thus would probably have had a yield in the kiloton range) but its yield was insufficient to ignite the fusion reaction and it failed to boost in this test. This test may have been a predecessor to the W-48 design.
Later and lighter 155 mm designs were also developed. The W74 (canceled early in development), and the W-82/XM-785 shell. The W82 had a yield of up to 2 kilotons and weighed 43 kg (95 lb), but included a number of sophisticated additional features within this weight. Since it was capable of being fielded with a "neutron bomb" (enhanced radiation) option, which is intrinsically more complex than a basic nuclear warhead, and was in addition rocket boosted, the actual minimum nuclear package was substantially lighter than the weight of the complete round. Its overall length was 86 cm (34").
It is reported that designs least as small as 105 mm (4.1 inches) are possible. A hypothetical 105 mm system developed for use in an artillery shell would be about 50 cm (20 inches) long and weigh around 20 kg.
Compact nuclear artillery shells (208 mm and under) are based on a design approach called linear implosion. The linear implosion concept is that an elongated (football shaped) lower density subcritical mass of material can be compressed and deformed into a critical higher density 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. The Swift device is known to have been a linear implosion design.
It is quite likely, that should the suitcase bombs described by Lebed actually exist, that they would use this technology. It is clear that any of the 155 mm artillery shells, if shortened by omitting the non-essential conical ogive and fuze would fit diagonally in the package that Lebed describes, and the Swift device would fit easily. If the yield is as much as 10 kilotons, then the device would have to be fusion boosted.
A somewhat more sophisticated variation would extend the linear implosion concept to cylindrical implosion, in this case an oblate (squashed) spheroid, roughly discus-shaped, of plutonium would be embedded in a cylinder of high explosive which is initiated simultaneously around its perimeter. The cylindrically converging detonation would compress and deform the fissile mass into a sphere, that could be wider than the original thickness of the system. This type of design would make the flattest possible bomb design, perhaps as little as 5 cm. The only obvious application for such a device would be briefcase bomb, and would require a special development effort to create it.
Source of weapon and test details The Swords of Armageddon, by Chuck Hansen, Chuckelea Publishing, 1995.
A second chapter in the Soviet suitcase bomb affair began with a Congressional hearing on Russian espionage held by Rep. Dan Burton (R-Indiana) on 24 January 2000 in Washington, DC. Soviet ex-colonel and GRU operative Stanislav Lunev was the star witness at the sparsely attended Military Research and Development Subcommittee hearing, chaired by Rep. Curt Weldon (R-Penn.).
Featured at the hearing was a mock-up of a notional briefcase bomb. In his opening comments Weldon described this exhibit:
The model is based on unclassified data on the components in an atomic artillery shell, to see if such a system could be reassembled in a suitcase. Indeed, as it turns out, the physics package, neutron generators, batteries, arming mechanism and other essentials of a small atomic weapon can fit, just barely, in an attache case. The result is a plutonium-fueled gun-type atomic weapon having a yield of one-to-ten kilotons, the same yield range attributed by General Lebed to the Russian "nuclear suitcase" weapon..
Presumably Weldon's reference to it being "gun-type" refers to it being fired from a gun, not its assembly method.
|Mock-up of a hypothetical "suitcase" nuclear bomb, made by Congressional|
staffer Peter Pry. It is basically a 105 mm artillery shell device packaged in a
The key point of the hearing was Lunev's additional allegations that nuclear suitcase bombs may have been pre-positioned in NATO countries during the Cold War, in a manner similar to the way other espionage resources including conventional explosives were known to have been cached.
Weldon summarized Lunev's claims:
Lunev defected to the United States in 1992 after working for more than a decade in the U.S. as a GRU operative. Lunev participated in a GRU program collecting information on the President and senior U.S. political and military leaders so they may be targeted for assassination in the event of war. According to Lunev, small man-portable nuclear weapons "that could be disguised to look like a suitcase" would be employed in a decapitating Russian attack against U.S. leaders and key communications and military facilities. Colonel Lunev claimed that the Russian military and intelligence services still regard the United States as the enemy and consider war with the U.S. as "inevitable."
Colonel Lunev stated that man-portable nuclear weapons may already be located in the United States. Lunev's claim is based on his understanding of GRU doctrine for employing these weapons, which calls for pre-positioning nuclear weapons in the United States during peacetime, before a crisis or war makes penetration of the U.S. more difficult. Lunev testified that he actively supported the GRU program to pre-position man-portable nuclear weapons in the United States by identifying in the U.S. potential hiding places where such weapons could be stored and concealed until needed. Lunev was specially trained to disguise and camouflage such weapons.
One account of the hearing ran as follows:
"Ex-Spy Testifies in Hearing", Linda Deutsch, AP Special Correspondent, Tuesday, Jan. 25, 2000; 3:59 a.m. EST
Much of Lunev's testimony was a repeat of allegations made in his 1998 book in which he said Russia's post-Cold War leaders still see the United States as the enemy.
Lunev, who is in the federal witness protection program, said he masqueraded as a reporter for the Russian news agency ITAR-Tass for three years during which he scouted "drop sites" for weapons caches in the U.S. But he said he has no idea if they were ever planted.
Rep. Curt Weldon, R-Pa., suggested in November that the spy caches might include suitcase-sized nuclear weapons that can produce a 10-kiloton blast.
Weldon, who also testified Monday, stood at one point, holding up a large briefcase and announced: "I have a small atomic demolition device I'd like to bring up to you."
Burton quickly reassured the audience that it was "a mockup" created by the CIA.
Russian officials have confirmed their arsenal includes such devices, but investigators have said there is no evidence they are part of the purported hidden stockpiles.
This hearing has most recently reached public attention when it was recounted in the October 2, 2001 edition of the National Enquirer, page 16.