"Biological weapons are the poor man's atomic bomb" - Hahsemi Rafsanjani, Speaker of the Iranian Parliament, 1988.
Of the many pathogens or biological agents available to the terrorist, anthrax and smallpox head the list. In terms of ease of production, stability and dispersal viability, these agents are the weapons of choice for the terrorist. Anatoliy Vorobyov, the former Russian bio-weapons expert, has confirmed anthrax and smallpox as the agents most likely to be used in a terrorist attack.
Both of these agents were produced and stored in the Russian bio-weapon facility code-named "Vector" and based in Koltsovo, Novosibirsk. Once protected by an elite guard and staffed by 4,000 chemists, this facility is now half-empty and rather less secure.
It can be added to a growing list of facilities and countries producing biological and chemical weapons.
These are believed to include Iran, Iraq, Serbia, Israel, Egypt, Sudan, Syria, China, Taiwan, Vietnam, Libya, North Korea, Cuba, Romania, Bulgaria, Pakistan, India and South Africa. Given the number of potential producers of chemical and biological agents, it is of little surprise that groups such as al-Qaeda could easily acquire such weapons.
The Japanese cult Aum Shinriko used Sarin nerve gas in the Tokyo subway attack of 1995. They also had plans to use biological agents. Members of the group travelled to Zaire in 1992 to obtain samples of Ebola virus for weapons development.
Given this precedent and the suicidal nature of the World Trade Centre attacks, it was always likely that the present terrorist network would resort to bio-terrorism. Anthrax in its natural state would normally be contracted through contact with animal hides or skins. Unfortunately, it lends itself well to development as a biological weapon.
Bacillus anthracis (anthrax) spores are extremely durable and capable of withstanding extremes of temperature and humidity. The spores are easily dispersed by aerosol and can be easily concealed and transported in powder form. The clinical features of anthrax include a five-day incubation period and infection occurs in cutaneous, gastro-intestinal or respiratory form.
Cutaneous, or skin infection, is the most common route of infection and is caused by touch. It is the least dangerous type of anthrax infection and can be readily treated by antibiotics. Gastro-intestinal anthrax is caused by ingestion or swallowing and causes haematemesis and bloody diarrhoea.
Respiratory anthrax is the most serious route of infection and is caused by inhalation - typically by sniffing a suspicious powder or dust. Once known as "Woolsorter's disease" - as it was associated with proximity to sheep - respiratory anthrax can lead to the abrupt onset of dyspnoea, cyanosis and death. In other words, if untreated, fluid builds up in the lungs, leading to respiratory failure and death.
Meanwhile, smallpox is caused by a virus spread from person to person. Unlike the bacteriological agent anthrax, smallpox, a viral agent, cannot be treated by antibiotics.
The incubation period for the condition is approximately 10-12 days and leads to high fever and a painful rash. There is no specific treatment for the condition and the mortality rate lies between 25 per cent and 35 per cent of unvaccinated patients.
Originally designed for use on the conventional battlefield, there are a number of key difficulties associated with the use of biological and chemical agents. The principal difficulty lies in the area of dispersal.
Most conventional forces will resort to artillery, missile or aerial dispersal. Even with sophisticated weapons systems there is the problem of predictability and viability. Factors as diverse as weather conditions and area-weapon accuracy can neutralise the effect of "temporary" agents. More persistent agents are considered unacceptable because of their lethal and uncontrollable effect. Military doctrine in most conventional forces dictates that the use of chemical and biological weapons is inadvisable for practical as well as political reasons. Quite simply, the cost benefit analysis of reliability to danger to friendly forces renders them non-viable.
For the terrorist, unconcerned with practical or political considerations, delivery and dispersal pose the main challenge. The terrorist must rely on man-portable delivery systems and more primitive interventions in order to expose the maximum number of victims to chemical or biological agents.
In the case of the United States, this would seem to include the use of the US postal system to send powder to high profile targets. The attacks are designed to have a profound psychological effect on the civilian population. In short, they are designed to instil fear, paranoia and panic. This would seem to have been achieved.
It is likely the terrorists will select other high profile targets in Britain and the Continent. The targets chosen will have been symbolically and emotionally loaded. The terrorist may select weak points in the food distribution system - targeting especially sensitive products such as baby foods or medicines.
They may also target financial districts with their enclosed metro and subway systems along with multi-storey office blocks. They may target hospitals. The primary objective is to instil fear and suspicion. The main threat to Ireland would be in the form of a spread of infection or contamination in the wake of such an attack in Britain.
The best defence in the event this type of attack is vigilance on the part of the authorities and the medical profession.
The early detection and containment of a biological attack will minimise its physical effects. In terms of the psychological effect, there is an urgent requirement for education, information and debate.
The lack of clarity in relation to this threat is generating as much fear and anxiety among the population as the threat itself.
Recent debates about the risk posed by attacks on Sellafield highlight people's latent fears. At present, there is no clearly identifiable agency or government minister tasked with dealing with this disturbing phenomenon. There is talk of a "co-ordinating committee" and perhaps even an "information leaflet". In the same way that the terrorist has exploited the media in order to spread fear and anxiety, the government might use the mass media to disseminate information and reassure the public.
What is needed now is timely, accurate information about the nature of the threat, its likely mechanism and our best means of protection.
Tom Clonan is a former Army captain. He now lectures in the political economy of communications in the Institute of Technology, Tallaght.