David Hafemeister is a physics professor at California Polytechnic State University, but this academic year he's at Stanford University studying ways to keep the Comprehensive Test Ban Treaty viable for the U.S. Senate to consider ratifying. Jonathan Farley, a professor in the mathematics and computer science deparment at the University of the West Indies, is here this year as well, conducting a mathematical analysis of counterterrorism operations. They are among seven science fellows now visiting the Center for International Security and Cooperation (CISAC), part of the Freeman Spogli Institute for International Studies at Stanford.

With fellowships in the sciences and social sciences, CISAC, directed by political science Professor Scott Sagan, brings top scholars to campus to find solutions to complex international problems.

This year's fellows "are a select and exciting set of scholars doing innovative work on important issues of international security--which now includes homeland security," said Lynn Eden, CISAC's associate director for research. "All of us at CISAC are very much looking forward to having our new crew on board."

The other CISAC science fellows are:

• Manas Baveja and Yifan Liu, both doctoral candidates at the Institute for Computational and Mathematical Engineering at Stanford, who use mathematical models to study homeland security;
• Chaim Braun of Altos Management Partners, who is working on a United Nations nuclear energy project;
• Belkis Cabrera-Palmer, a physics doctoral candidate from Syracuse University, who is studying nuclear energy issues in Latin America; and
• Sonja Schmid, a lecturer in Stanford's Science, Technology and Society Program, who is working on a book aimed at understanding the decisions that produced and sustained the civilian nuclear energy program in the Soviet Union from the 1950s through the 1980s.

Charles Perrow, professor emeritus of sociology from Yale University, is among seven pre- and postdoctoral fellows in social science disciplines who are also visiting CISAC. Perrow is working on a project to reduce homeland security vulnerabilities. CISAC's other postdoctoral social science fellows are:

• Tarak Barkawi, a lecturer at the Centre for International Studies at the University of Cambridge in England, who is examining why small wars have big consequences, and
• Alex Montgomery, a doctoral candidate in political science at Stanford, whose project deals with U.S. post-Cold War nuclear counterproliferation strategies.

CISAC's predoctoral fellows in social science are:

• Dara Cohen, a doctoral candidate in political science at Stanford, who will examine the efficacy of post-9/11 domestic security legislation;
• Matthew Rojansky, a law student at Stanford, whose project explores the legitimacy of international institutions and legal instruments in the war on terror;
• Jacob Shapiro, a doctoral candidate in political science at Stanford, whose project looks at the organizational consequences of terrorist motivation; and
• Jessica Stanton, a doctoral candidate in political science at Columbia University, who is examining compliance with international laws of war during civil war.

CISAC also is hosting Robert Carlin of the Korean Peninsula Energy Development Organization, a visiting scholar whose project addresses U.S.-North Korea relations, and Laura Donohue, who is writing a book, Counterterrorism and the Death of Liberalism, while completing a law degree at Stanford Law School. Patrick Roberts, who comes to Stanford from the University of Virginia, where he earned a doctorate in politics, will examine bureaucratic autonomy and homeland security reorganization.

Amid uncertainty over the outcome of the six-party negotiations on North Korea's nuclear weapons development, public concern is likely to focus on whether Pyongyang will live up to commitments it made to dismantle its nuclear weapons programme (already questionable) and whether it will pursue long-range nuclear missiles that could destroy an American city or, more immediately, Seoul and Tokyo. But the latter concern is not the most effective nuclear threat North Korea or other potential adversaries could pose.

A nuclear threat to American cities, if implemented, would certainly provoke massive US retaliation. There are better options for opponents: credible, cheaper and more suited to the US capabilities that adversaries would face. Since the cold war, the top US military priority, as stated in congressional testimonies, has been to deploy the world's most effective power projection forces. These forces have been used in the Balkans, the Persian Gulf and central Asia. A power projection force operates in or near hostile territory. It must rely on superior training, tactics and equipment. Joint force training, mobile communication and control, soldiers capable of individual initiative and precision-guided munitions have been key to US success.

Any power projection force needs air bases and ports of debarkation and logistics centres for sustained operations. These facilities must be rented or conquered. Their number is limited - a handful in Iraq, and not many more in east Asia, seven or so in Japan, some bases in South Korea, and a few others. These facilities are highly vulnerable even to inaccurate nuclear missile attacks. They are "soft targets", not "hardened" against nuclear weapons.

North Korea, with a couple of dozen warheads mounted on its intermediate-range No Dong missiles, or its longer-range Taepo Dong missiles, could threaten all the US assets mentioned above and have weapons left to threaten Tokyo and Seoul.

The US could destroy those North Korean military and nuclear assets it could locate. North Korean forces could retreat into the mountains and position for a protracted ground war. But would the US then launch a massive attack against North Korea with the threat still hanging over Japanese and South Korean cities?

The Pentagon's Quadrennial Defense Review envisages a force structure better suited to counter-terrorism and control of the seas and the sky, rather than focused on fighting two land wars simultaneously. The nuclear threat to essential US force-projection assets largely counterbalances the advantage provided by US conventional forces, without necessarily consigning whole cities and industrial bases to destruction. That latter threat can still be held in reserve by our adversaries.

Should this threat mature, it would undercut the credibility of US security guarantees in east Asia that have been the hallmark of US strategy in the region for more than half a century. Japan, South Korea and Taiwan all depend heavily on these guarantees for their security. This credibility has dissuaded each government from acquiring its own nuclear force. Such restraint, in turn, has permitted China to proceed at a more measured pace in its own nuclear weapons development programmes.

If key political and defence officials in Tokyo, Seoul and Taipei no longer believed in US guarantees because of the vulnerability of US military assets in the region to a North Korean nuclear missile attack, the consequences for their own security and for US national strategy could be profound. Although circumstances are quite different in the Middle East-Persian Gulf region, similar consequences could materialise if Iran or another hostile country developed a comparable nuclear missile capability.

A great deal is at stake in constraining the missile and nuclear weapons capabilities of North Korea and other rogue states. The US thus must utilise all the resources at its disposal, working constructively with its allies and other interested parties, to deny these states the capabilities they almost surely seek to acquire. A more resilient forward defence and deterrent posture is essential to an effective American global strategy.

A new united nations report recommending the most sweeping reform in the institution's history offers a global vision of collective security for the 21st century that is as committed to development in poor nations as it is to prevention of nuclear terrorism in rich ones.

The point is, according to the report's research director, Stephen Stedman, a threat to one is a threat to all in today's world. "Globalization means that a major terrorist attack anywhere in the industrial world would have devastating consequences for the well-being of millions around the developing world," the document states. The report's value lies in putting forward a comparative framework of collective security that addresses all the compelling threats of the day, Stedman explained. "The recommendations really are the most important possible makeover of the institution in 60 years," he said. "I think something is going to come out of it." Stedman, a senior fellow at the Center for International Security and Cooperation (CISAC) at the Stanford Institute for International Studies (SIIS), was recruited a year ago by U.N. Secretary General Kofi Annan to direct research for the High-Level Panel on Threats, Challenges, and Change. Stedman is an expert on civil wars, mediation, conflict prevention, and peacekeeping.

Annan created the 16-member blue-ribbon panel, made up mostly of former government leaders and ministers, in the wake of widespread heated criticism of the United Nations following the U.S.-led war in Iraq. In Annan's annual report to the General Assembly in 2003, he said, "Rarely have such dire forecasts been made about the U.N. ... We have reached a fork in the road ... a moment no less decisive than 1945 itself, when the U.N. was founded." The panel was charged with analyzing global security threats and proposing far-reaching reforms to the international system.

On December 2 the panel, chaired by former Thai prime minister Anand Panyarachun, issued its 95-page report: "A More Secure World: Our Shared Responsibility." The document identifies six major threats to global security:

-War between states;

-Violence within states, including civil wars, large-scale human rights abuses, and genocide;

-Poverty, infectious disease, and environmental degradation;

-Nuclear, radiological, chemical, and biological weapons;

-Terrorism; and

-Transnational organized crime.

Although states do not face these threats equally, a collective security system must take all member states' threats seriously and deal with them equitably, the report noted. It specifically mentioned the world's appallingly slow response to AIDS.

The report makes 101 recommendations for collective prevention and response to the threats, including ways to reform the United Nations. Annan described these in a December 3 editorial in the International Herald Tribune as "the most comprehensive and coherent set of proposals for forging a common response to common threats that I have seen."

The document also reaffirms the right of states to defend themselves-even preemptively-when an attack is imminent, and it offers guidelines to help the Security Council decide when to authorize the use of force. Stedman said other significant proposals involve improving biosecurity, strengthening nuclear nonproliferation, and defining terrorism. Panel members agreed that any politically motivated violence against civilians should be regarded as terrorism and condemned.

The panel was very critical of the Human Rights Commission, a body that has often harmed the United Nations' reputation by permitting the membership of some of the worst human-rights violators, including Cuba, Libya, and Sudan. The report also discussed the need for new institutions, such as a peace-building commission, that would support countries emerging from conflict.

Scott Sagan, co-director of CISAC, described the report as hard-hitting, although he said he would have tried to extend the withdrawal clause of the nonproliferation treaty from three months to a year. "I think it's the beginning of some major changes that will be helpful," he said. "We need to get states to work together to reform the U.N. rather than sniping at it."

CISAC was closely involved in the panel's work and was named in a cover letter accompanying the report from Panyarachun to Annan. Co-director Chris Chyba served on the panel's 30-member resource group, providing expertise on nuclear nonproliferation and bioterrorism. Bruce Jones, a former CISAC Hamburg Fellow, acted as Stedman's deputy, and Tarun Chhabra, a graduate of CISAC's undergraduate honors program and recent Marshall Scholarship recipient, worked as a research officer. Political science Professors David Laitin and James Fearon, and SIIS Senior Fellow David Victor, provided, respectively, expertise on terrorism, civil wars, and the environment, Stedman said. "There is an immense amount of Stanford influence in the report," he added.

CISAC also hosted a nuclear nonproliferation workshop for the panel on campus last March and helped organize a meeting during the summer in Bangkok. SIIS co-hosted a conference on governance and sovereignty on campus in April and a meeting at Oxford University in June. CISAC provided workspace to give the research team a quiet place to focus on writing the report's first draft in August.

The report has attracted intense international media interest in part because it calls for expanding the U.N. Security Council, its top decision-making group, from 15 to 24 members. The panel was unable to agree on one proposal and offers two options that would make the council more representative and democratic. "I believe either formula would strengthen the legitimacy in the eyes of the world, by bringing its membership closer to the realities of the 21st century-as opposed to those of 1945, when the U.N. Charter was drafted," Annan wrote in the International Herald Tribune.

According to Stedman, the media has highlighted the Security Council's proposed expansion because so many nations have a stake in it. "But in the absence of a new consensus on international peace and security, expansion of the council will not be effective," he explained.

In March, Annan will use the report to inform a series of proposals he will present to the 191 U.N. member states. These, in turn, will be submitted to a summit of world leaders before the General Assembly convenes next September in New York. Stedman said he has been asked to stay on for another year as a special advisor to the secretary general to keep the United Nations "on message" during negotiations.

Engagement by the United States, which has openly questioned the institution's relevance, will be critical to implementing the report's recommendations, said Stedman, who added that the superpower can benefit from a revamped United Nations. "Putting threats to the United States into a global framework makes it more secure," he said.

Stedman noted that one of the most disturbing aspects of the panel's consultations was listening to government representatives from civil-society organizations dismiss the seriousness of bio- and nuclear terror threats against the United States. "They were essentially denying this as a real threat to American security," he said. "I said it's as real a threat to the U.S. as other threats are to you."

When Stedman accepted the job, he thought he would spend 80 percent of his time on research and writing and 20 percent on consultations and negotiating. In fact, he said, it was the other way around. "It's unlike anything I've ever done," he said. "It's been a blast." In contrast to academia, where a researcher presents his or her best findings and defends them, Stedman was faced with 16 people who would push back, reject, or accept his work. "I had to work to change language to include their concerns," he said. "My biggest concern at the beginning was that the report would be based on the lowest common denominator. It's not."

Stedman said the panel members remained open-minded throughout the year. "They showed flexibility, listened to arguments, and changed their minds," he said. "Our job was to be as persuasive, rigorous, and comprehensive in our analysis as we were able to achieve."

In the end, Stedman said, the report belongs to the panel. "Parts of what the exercise shows is that access to those making policy is really important," he said. "If you do really good work and you have access, you have a chance of being heard. Kofi Annan gave me that opportunity."

Two of the 10 Stanford University undergraduates who completed CISAC's Interschool Honors Program in International Security Studies this year earned awards for their theses.

Sheena Elise Chestnut, a political science major, received a Firestone Medal for her thesis, "The 'Sopranos State'? North Korean Involvement in Criminal Activity and Implications for International Security." The Firestone Medal recognizes the top 10 percent of Stanford University's undergraduate honors theses.

Jessica McLaughlin, a management science and engineering major, received the William J. Perry Award for her thesis, "A Bayesian Updating Model for Intelligence Analysis: A Case Study of Iraq's Nuclear Weapons Program." The Perry Award recognizes excellence in policy-relevant research in international security studies.

In a June graduation ceremony outside Stanford University's Encina Hall, CISAC faculty member Mariano-Florentino Cuéllar, CISAC Postdoctoral Fellow Tonya L. Putnam, and CISAC Co-Director Scott D. Sagan presented students with certificates and thesis awards.

At a CISAC Directors' Seminar on June 1, Chestnut and McLaughlin presented their award-winning theses to an audience of 50 fellow students, faculty members and guests. Chestnut also gave a special seminar at CISAC in May, hosted by APARC and the Preventive Defense Project at CISAC.

The names, majors and thesis titles of eight others who completed the CISAC honors program are

Zack Cooper, public policy, Roman and British Experiences with Maritime Piracy and Implications for Combating Terrorism Today

Nina Hsu, political science, Chinese Assistance in the Pakistani Nuclear Program

Sohan Japa, biomechanical engineering, A Path to Peril: Understanding the Technical Hurdles of Biological Weapon Production

Bradley Larson, political science, Soft Power: US Foreign Aid Post-9/11

Frances Lewis, international relations, The Yellow Light Reactor: An Explanation of the Stop and Go Progress at Bushehr

Victor Marsh II, international relations, A Responsibility to Consult? Local Policy Ownership During Transitional Governance

Christopher Williams, physics, Closing the Nuclear Fuel Cycle: A Component Based Analysis of Options for Spent Fuel Management"

Ming Zhu, international relations, Power and Cooperation: Understanding the Road Towards a Truth Commission

Begun in 2000 to help develop the next generation of security specialists, CISAC's honors hrogram accepts 12 to 14 Stanford undergraduates each year, from any disciplines. Those selected attend a two-week CISAC honors college in Washington, D.C., complete an internship with a security-related organization, attend a year-long core seminar on international security research and produce an honors thesis with policy implications for international security. After fulfilling their individual department course requirements and completing the honors program, participants graduate in their major with an honors certificate in international security studies.

In 1920, the Irish Republican Army reportedly considered a terrifying new weapon: typhoid-contaminated milk. Reading from an IRA memo he claimed had been captured in a recent raid, Sir Hamar Greenwood described to Parliament the ease with which "fresh and virulent cultures" could be obtained and introduced into milk served to British soldiers. Although the plot would only target the military, the memo expressed concern that the disease might spread to the general population.

Although the IRA never used this weapon, the incident illustrates that poisoning a nation's milk supply with biological agents hardly ranks as a new concept. Yet just two weeks ago, the National Academy of Sciences' journal suspended publication of an article analyzing the vulnerability of the U.S. milk supply to botulinum toxin, because the Department of Health and Human Services warned that information in the article provided a "road map for terrorists."

That approach may sound reasonable, but the effort to suppress scientific information reflects a dangerously outdated attitude. Today, information relating to microbiology is widely and instantly available, from the Internet to high school textbooks to doctoral theses. Our best defense against those who would use it as a weapon is to ensure that our own scientists have better information. That means encouraging publication.

The article in question, written by Stanford University professor Lawrence Wein and graduate student Yifan Liu, describes a theoretical terrorist who obtains a few grams of botulinum toxin on the black market and pours it into an unlocked milk tank. Transferred to giant dairy silos, the toxin contaminates a much larger supply. Because even a millionth of a gram may be enough to kill an adult, hundreds of thousands of people die. (Wein summarized the article in an op-ed he wrote for the New York Times.) The scenario is frightening, and it is meant to be -- the authors want the dairy industry and its federal regulators to take defensive action.

The national academy's suspension of the article reflects an increasing concern that publication of sensitive data can provide terrorists with a how-to manual, but it also brings to the fore an increasing anxiety in the scientific community that curbing the dissemination of research may impair our ability to counter biological threats. This dilemma reached national prominence in fall 2001, when 9/11 and the anthrax mailings drew attention to another controversial article. This one came from a team of Australian scientists.

Approximately every four years, Australia suffers a mouse infestation. In 1998, scientists in Canberra began examining the feasibility of using a highly contagious disease, mousepox, to alter the rodents' ability to reproduce. Their experiments yielded surprising results. Researchers working with mice naturally resistant to the disease found that combining a gene from the rodent's immune system (interleukin-4) with the pox virus and inserting the pathogen into the animals killed them -- all of them. Plus 60 percent of the mice not naturally resistant who had been vaccinated against mousepox.

In February 2001 the American SocietyforMicrobiologists' (ASM) Journal of Virology reported the findings. Alarm ensued. The mousepox virus is closely related to smallpox -- one of the most dangerous pathogens known to humans. And the rudimentary nature of the experiment demonstrated how even basic, inexpensive microbiology can yield devastating results.

When the anthrax attacks burst into the news seven months later, the mousepox case became a lightning rod for deep-seated fears about biological weapons. The Economist reported rumors about the White House pressuring American microbiology journals to restrict publication of similar pieces. Samuel Kaplan, chair of the ASM publications board, convened a meeting of the editors in chief of the ASM's nine primary journals and two review journals. Hoping to head off government censorship, the organization -- while affirming its earlier decision -- ordered its peer reviewers to take national security and the society's code of ethics into account.

Not only publications came under pressure, but research itself. In spring 2002 the newly formed Department of Homeland Security developed an information-security policy to prevent certain foreign nationals from gaining access to a range of experimental data. New federal regulations required that particular universities and laboratories submit to unannounced inspections, register their supplies and obtain security clearances. Legislation required that all genetic engineering experiments be cleared by the government.

On the mousepox front, however, important developments were transpiring. Because the Australian research had entered the public domain, scientists around the world began working on the problem. In November 2003, St. Louis University announced an effective medical defense against a pathogen similar to -- but even more deadly than -- the one created in Australia. This result would undoubtedly not have been achieved, or at least not as quickly, without the attention drawn by the ASM article.

The dissemination of nuclear technology presents an obvious comparison. The 1946 Atomic Energy Act classifies nuclear information "from birth." Strong arguments can be made in favor of such restrictions: The science involved in the construction of the bomb was complex and its application primarily limited to weapons. A short-term monopoly was possible. Secrecy bought the United States time to establish an international nonproliferation regime. And little public good would have been achieved by making the information widely available.

Biological information and the issues surrounding it are different. It is not possible to establish even a limited monopoly over microbiology. The field is too fundamental to the improvement of global public health, and too central to the development of important industries such as pharmaceuticals and plastics, to be isolated. Moreover, the list of diseases that pose a threat ranges from high-end bugs, like smallpox, to common viruses, such as influenza. Where does one draw the line for national security?

Experience suggests that the government errs on the side of caution. In 1951, the Invention Secrecy Act gave the government the authority to suppress any design it deemed detrimental to national defense. Certain areas of research-- atomic energy and cryptography -- consistently fell within its purview. But the state also placed secrecy orders on aspects of cold fusion, space technology, radar missile systems, citizens band radio voice scramblers, optical engineering and vacuum technology. Such caution, in the microbiology realm, may yield devastating results. It is not in the national interest to stunt research into biological threats.

In fact, the more likely menace comes from naturally occurring diseases. In 1918 a natural outbreak of the flu infected one-fifth of the world's population and 25 percent of the United States'. Within two years it killed more than 650,000 Americans, resulting in a 10-year drop in average lifespan. Despite constant research into emerging strains, the American Lung Association estimates that the flu and related complications kill 36,000 Americans each year. Another 5,000 die annually from food-borne pathogens -- an extraordinarily large number of which have no known cure. The science involved in responding to these diseases is incremental, meaning that small steps taken by individual laboratories around the world need to be shared for larger progress to be made.

The idea that scientific freedom strengthens national security is not new. In the early 1980s, a joint Panel on Scientific Communication and National Security concluded security by secrecywasuntenable. Its report called instead for security by accomplishment -- ensuring strength through advancing research. Ironically, one of the three major institutions participating was the National Academy of Sciences -- the body that suspended publication of the milk article earlier this month.

The government has a vested interest in creating a public conversation about ways in which our society is vulnerable to attack. Citizens are entitled to know when their milk, their water, their bridges, their hospitals lack security precautions. If discussion of these issues is censored, the state and private industry come under less pressure to alter behavior; indeed, powerful private interests may actively lobby against having to install expensive protections. And failure to act may be deadly.

Terrorists will obtain knowledge. Our best option is to blunt their efforts to exploit it. That means developing, producing and stockpiling effective vaccines. It means funding research into biosensors -- devices that detect the presence of toxic substances in the environment -- and creating more effective reporting requirements for early identification of disease outbreaks. And it means strengthening our public health system.

For better or worse, the cat is out of the bag -- something brought home to me last weekend when I visited the Tech Museum of Innovation in San Jose. One hands-on exhibit allowed children to transfer genetic material from one species to another. I watched a 4-year-old girl take a red test tube whose contents included a gene that makes certain jellyfish glow green. Using a pipette, she transferred the material to a blue test tube containing bacteria. She cooled the solution, then heated it, allowing the gene to enter the bacteria. Following instructions on a touch-screen computer, she transferred the contents to a petri dish, wrote her name on the bottom, and placed the dish in an incubator. The next day, she could log on to a Web site to view her experiment, and see her bacteria glowing a genetically modified green.

In other words, the pre-kindergartener (with a great deal of help from the museum) had conducted an experiment that echoed the Australian mousepox study. Obviously, this is not something the child could do in her basement. But just as obviously, the state of public knowledge is long past anyone's ability to censor it.

Allowing potentially harmful information to enter the public domain flies in the face of our traditional way of thinking about national security threats. But we have entered a new world. Keeping scientists from sharing information damages our ability to respond to terrorism and to natural disease, which is more likely and just as devastating. Our best hope to head off both threats may well be to stay one step ahead.

While the anthrax scare at Washington Post offices this year proved to be a false alarm, it was a reminder of how vulnerable Americans are to biological terrorism. In general, two threats are viewed as the most dangerous: anthrax, which is as durable as it is deadly, and smallpox, which is transmitted very easily and kills 30 percent of its victims.

But there is a third possibility that, while it seems far more mundane, could be just as deadly: terrorists spreading a toxin that causes botulism throughout the nation's milk supply.

Why milk? In addition to its symbolic value as a target--a glass of milk is an icon of purity and healthfulness--Americans drink more than 6 billion gallons of it a year. And because it is stored in large quantities at centralized processing plants and then shipped across country for rapid consumption, it is a uniquely valuable medium for a bioterrorist.

For the last year, a graduate student, Yifan Liu, and I have been studying how such an attack might play out, and here is the situation we consider most likely: a terrorist, using a 28-page manual called "Preparation of Botulism Toxin" that has been published on several jihadist Web sites and buying toxin from an overseas black-market laboratory, fills a one-gallon jug with a sludgy substance containing a few grams of botulin. He then sneaks onto a dairy farm and pours its contents into an unlocked milk tank, or he dumps it into the tank on a milk truck while the driver is eating breakfast at a truck stop.

This tainted milk is eventually piped into a raw-milk silo at a dairy-processing factory, where it is thoroughly mixed with other milk. Because milk continually flows in and out of silos, approximately 100,000 gallons of contaminated milk go through the silo before it is emptied and cleaned (the factories are required to do this only every 72 hours). While the majority of the toxin is rendered harmless by heat pasteurization, some will survive. These 100,000 gallons of milk are put in cartons and trucked to distributors and retailers, and they eventually wind up in refrigerators across the country, where they are consumed by hundreds of thousands of unsuspecting people.

It might seem hard to believe that just a few grams of toxin, much of it inactivated by pasteurization, could harm so many people. But that, in the eye of the terrorists, is the beauty of botulism: just one one-millionth of a gram may be enough to poison and eventually kill an adult. It is likely that more than half the people who drink the contaminated milk would succumb.

The other worrisome factor is that it takes a while for botulism to take effect: usually there are no symptoms for 48 hours. So, based on studies of consumption, even if such an attack were promptly detected and the government warned us to stop drinking milk within 24 hours of the first reports of poisonings, it is likely that a third of the tainted milk would have been consumed. Worse, children would be hit hardest: they drink significantly more milk on average than adults, less of the toxin would be needed to poison them and they drink milk sooner after its release from dairy processors because it is shipped directly to schools.

And what will happen to the victims? First they will experience gastrointestinal pain, which is followed by neurological symptoms. They will have difficulty seeing, speaking and walking as paralysis sets in. Most of those who reach a hospital and get antitoxins and ventilators to aid breathing would recover, albeit after months of intensive and expensive treatment. But our hospitals simply don't have enough antitoxins and ventilators to deal with such a widespread attack, and it seems likely that up to half of those poisoned would die.

As scary as this possibility is, we have actually been conservative in some of our assumptions. The concentration of toxin in the terrorists' initial gallon is based on 1980's technology and it's possible they could mix up a more potent brew; there are silos up to four times as large as the one we based our model on, and some feed into several different processing lines that would contaminate more milk; and the assumption that the nationwide alarm could go out within 24 hours of the first reported symptoms is very optimistic (two major salmonella outbreaks in the dairy industry, in 1985 and 1994, went undetected for weeks and sickened 200,000 people).

What can we do to avoid such a horror? First, we must invest in prevention. The Food and Drug Administration has some guidelines - tanks and trucks holding milk are supposed to have locks, two people are supposed to be present when milk is transferred - but they are voluntary. Let's face it: in the hands of a terrorist, a dairy is just as dangerous as a chemical factory or nuclear plant, and voluntary guidelines are not commensurate with the severity of the threat. We need strict laws - or at least more stringent rules similar to those set by the International Organization for Standardization in Geneva and used in many countries - to ensure that our milk supply is vigilantly guarded, from cow to consumer.

Second, the dairy industry should improve pasteurization so that it is far more potent at eliminating toxins. Finally, and most important, tanks should be tested for toxins as milk trucks line up to unload into the silo. The trucks have to stop to be tested for antibiotic residue at this point anyway, and there is a test that can detect all four types of toxin associated with human botulism that takes less than 15 minutes. Yes, to perform the test four times, once for each toxin, on each truck would cost several cents per gallon. But in the end it comes down to a simple question: isn't the elimination of this terrifying threat worth a 1 percent increase in the cost of a carton of milk?

One other concern: although milk may be the obvious target, it is by no means the only food product capable of generating tens of thousands of deaths. The government needs to persuade other food-processing industries - soft drinks, fruit juices, vegetable juices, processed-tomato products - to study the potential impact of a deliberate botulin release in their supply chains and take steps to prevent and mitigate such an event.

Americans are blessed with perhaps the most efficient food distribution network in history, but we must ensure that the system that makes it so easy to cook a good dinner doesn't also make it easy for terrorists to kill us in our homes.