CIAO DATE: 11/01

International — Nuclear Terrorism

In Perspective©
The Oxford Analytica Weekly Column
November 19, 2001

Oxford Analytica

Taliban leader Mullah Mohammed Omar on November 15 threatened widespread destruction in the United States. Mullah Omar's ambiguous threat of large-scale destruction and Osama bin Laden's explicit claim to possess nuclear weapons raise questions about the likelihood of nuclear terrorism and highlight the importance of protecting sources of highly enriched uranium and plutonium.

Technical barriers need not be considered sufficient to prevent the use of nuclear devices by terrorist groups. Nuclear weapon standards are much lower for terrorist groups than for states, potentially making their production less challenging. Acquisition of sufficient qualities and quantities of fissile material is the most formidable obstacle to nuclear terrorist capabilities. Therefore, stringent guarding of access to such material is the best defence against nuclear terrorism.

While conventional means are likely to remain the weaponry of choice for terrorists, the notion that nuclear terrorism is unlikely because it is too difficult is open to question. Technical challenges may not prove sufficient barriers to nuclear terrorist operations.

Assessing the technical capabilities of aspiring nuclear terrorists is paramount. The Pentagon is understood to be investigating al-Qaida's plans for nuclear devices, reportedly uncovered in partly burned papers in a house used by al-Qaida in Kabul. The papers are said to contain notes in Arabic, German, Urdu and English explaining how explosives compress plutonium and trigger a nuclear reaction.

Any aspiring nuclear actor must be able to:

• develop a design for the nuclear device or obtain such a design from a weapon-holding state;
• produce the fissile material for the core of the device or obtain it from an external source and then machine the fissile material to fabricate the nuclear parts of the weapon;
• fabricate, or obtain from outside sources, the non-nuclear parts of the device, including the high-explosive elements and triggering components that will detonate the nuclear core; and
• verify the reliability of these various elements individually and as a system, and finally assemble all of these elements into a deliverable nuclear armament — a process often dubbed 'weaponisation'.

Modest requirements. These necessary steps have led most analysts to conclude that significant technical hurdles stand in the way of the practice of nuclear terrorism in any form. However, the differing requirements of sovereign-military and terrorist nuclear devices could make such conclusions premature:

• Safety and yield. States are at least as concerned with the nuclear device not going off during storage and transportation as with optimising the yield and detonation of the weapon. For terrorists, such concerns could be given less consideration, especially among groups which espouse martyrdom.
• Reliability. Reliability would be a low priority for terrorists. By contrast, an ignition failure or a small yield would potentially be disastrous for a state launching a first nuclear strike. For terrorists, any explosion in the lower kiloton range represents an unprecedented success, and even failed plutonium explosives may serve as radiological dispersion devices.
• Delivery. Weapons for military uses must usually be delivered by conventional military means (missiles, mortars, etc). The most important constraining factors for state nuclear weapons are the weight capacity of the delivery vehicle and the accuracy of its navigation. Development of reliable delivery systems and compact nuclear explosives is technically challenging and expensive. Crude terrorist nuclear weapons, however, need only fit into a van or even a car. Other non-military means of delivery include trucks, hot-air balloons and ships.

The rapid spread of technological knowledge could be a boost to terrorists' weaponisation attempts. The design and production of nuclear weapons today is a far simpler process than it was during the Manhattan Project. Relevant nuclear weapons production information can be found in the technical literature.

Public domain. A book entitled 'The first lectures on how to build an atomic bomb' was declassified and published in 1992. The book originated as a series of five lectures given to physicists of the Manhattan Project at its commencement, outlining the theoretical foundations of bomb-making. To highlight the proliferation dangers and the potential for clandestine nuclear bomb production, nuclear scientists have presented simple, technical outlines of crude nuclear weapons. These weapons are allegedly capable of exploding with a yield equivalent to that of several hundred to a few thousand tons of TNT (the atomic bomb dropped on Hiroshima had a yield equivalent to 15,000 tons of TNT). Potential nuclear weapon producers can find useful sites on the internet as well. While these do not present step-by-step descriptions for nuclear weapon construction or acquisition, parts of the openly available information are likely to assist and even guide potential bomb-makers in the process.

The primary technical barrier to nuclear terrorism is therefore access to highly enriched uranium (HEU) or plutonium, the essential components of any nuclear weapon, in sufficient quantities and qualities. Nuclear weapons programmes require the backing of a state to support large and costly infrastructure for enrichment and/or reprocessing of fissile weapons material. This makes sub-national groups reliant on externally acquired weapons-usable materials. Estimates of the quantities of fissile material needed for weapon production vary, depending on expected yield performance and technical sophistication. While the International Atomic Energy Agency's (IAEA) 'significant quantities' thresholds are 25 kilograms of HEU and eight kilograms of plutonium, respectively, as little as one kilogram of plutonium and 2.5 kilograms of HEU may be sufficient with appropriately sophisticated weapon designs.

Smuggling incidents. In 1996, a summit of G7 leaders was called to address the threat of nuclear proliferation amid concerns that the international campaign to limit the proliferation of nuclear materials from the former Soviet Union was running out of steam. While the summit organisers assembled a package of measures and proposals to ensure the security of nuclear weapons and highly dangerous material, the final statement of the summit on nuclear security smoothed over differences between the G7 and Moscow — at the time anxious not to be viewed as making too many concessions to the West. The limited nature of the measures announced after the summit resulted in further momentum being lost in the international campaign to reduce the dangers of illegal proliferation.

According to the IAEA's Illicit Trafficking Database, about 600 illicit trafficking incidents have taken place since January 1, 1993. Of these, about 400 incidents are confirmed to have been undertaken by states. A little less than half of the confirmed cases (175) involve nuclear material, including 18 cases involving HEU or plutonium. None of the quantities of seized nuclear material is enough to produce a workable nuclear explosive and no final buyer has been identified. However, the seizures produce a disturbing picture, given that only one successful transfer of high-quality nuclear material need take place in order to have devastating consequences:

• The proportion of HEU and plutonium cases among illicit trafficking cases has remained relatively stable since the early 1990s, indicating a persistent market, or at least a remaining interest, in illicit fissile materials.
• Some of the material uncovered had already travelled across wide distances and through several border crossings, indicating the difficulties of detecting illicit unirradiated fissile material.
• The seized quantities may be test samples to be followed by larger purchases.
• The IAEA database by definition only tracks unsuccessful transfers; there is no way of knowing whether a successful transfer has taken place.

Terrorist groups with nuclear ambitions face considerable practical and strategic constraints. These include training and operational practices, possible stigmas damaging to any future political ambitions, and the threat of retaliatory extinction. Still, the use of crude HEU nuclear weapons provides the opportunity of a fairly reliable, distinct, prestigious and highly visible act of large-scale terrorism, without prior testing of the crude nuclear devices. The impact would be tremendous, both materially and psychologically. Even crude nuclear explosives have the potential to produce yields in the lower kiloton range, at least three orders of magnitude greater than the most powerful conventional explosives.