During a speech at a state-level homeland security conference, Rick Riesland warned that terrorists could use widely available disease agents such as those that cause foot-and-mouth disease to devastate the U.S. agricultural economy.

Although lone-wolf attackers or smaller extremist organizations could view biological attacks as a means of gaining notoriety, an attack against U.S. agriculture would lack the spectacle that al Qaeda prefers -- not to mention that such an attack would be unlikely to cause mass chaos.

A biological attack against cattle does not fit the conventional criteria for an al Qaeda operation. Unlike a bombing, a biological attack is a slow process that lacks a scene of destruction that can be easily broadcasted through the media. Although al Qaeda might create new tactical innovations, it prefers to bomb symbolic targets that can be recognized by and appeal to the average Muslim. Infecting a herd of cattle does not accomplish this.

Furthermore, even if al Qaeda had the logistics to successfully infect the food supply, only part of the supply would be affected. The planning and resource allocation involved in making a sizeable dent would be impossible even for hostile state actors, not to mention an al Qaeda cell operating in a hostile environment. It might be possible to manipulate the price of a given commodity for short periods based on public hysteria over a small-scale attack, but the effect would be minimal and short-term. Despite the preventative slaughter of thousands of cattle in Britain during the mad cow scares, for example, the British economy saw no significant impact as a result of the losses.

An attack against a country's agricultural infrastructure can be intended either to create famine or to directly poison a population through its food supply. To poison the food supply, attackers have two choices: Target the crops or animals prior to processing, or strike at the finished food product. The most recent threat scenario in Wyoming, for example, involves introducing a biological agent into the food supply though the clandestine distribution of tainted feed to cattle. An attack on the finished product, on the other hand, would bypass any sort of pasteurization or refinement that may cleanse the biological agent from the targeted product.

All biological terrorism cases known to date have been attempts to directly poison people, not to cause famine.

Because of the sheer size of the agriculture industry, it is much easier to poison end products than to try to poison raw food products. Not only is it logistically impractical for any terrorist organization to launch such a strike, but the cost-benefit ratio also would be too small. Running such a major operation, not to mention acquiring the substantial infrastructure needed to produce large quantities of agents, would be prohibitively costly. Then there is no guarantee that the affected product would make it to final human consumption because products often are converted to other, non-agricultural uses, such as ethanol gas.

The threat of an attack against agriculture is remote compared to threats against other infrastructure. Many of the agents that could be used in a biological attack against agriculture occur naturally, such as anthrax or plant blights. However, both the Food and Drug Administration and the Department of Agriculture long ago implemented safeguards to prevent these natural outbreaks of disease, while farmers have been monitoring their animals and crops for disease since farming began. There is no reason why such safeguards would not successfully prevent a manmade outbreak.

Making everything a potential target and arousing public paranoia distracts focus from the more credible threats.