This week President Bush will seek to focus the nation's attention on border security and immigration reform. But the president's proposals won't protect Americans from our gravest cross-border threat: the possibility that a ship, truck or train will one day import a 40-foot cargo container in which terrorists have hidden a dirty bomb or nuclear weapon.

The Bush administration maintains that it has a smart strategy to reduce this risk. A new 24-Hour Rule requires that importers report the contents of their containers to customs inspectors one day before the boxes are loaded on ships bound for the United States. The Department of Homeland Security's National Targeting Center then reviews the data, checking against other intelligence to determine which boxes may pose a threat. Although the containers deemed high risk are inspected at cooperating foreign ports or when they enter the United States, the rest--more than 90 percent--land here without any perusal.

We have two concerns about this strategy. First, it presumes that the United States government has good enough intelligence about Al Qaeda to reliably discern which containers are suspicious and which are not. But our inability to thwart the attacks in Iraq demonstrates that we lack such specific tactical intelligence. And supporting customs inspectors, who must make the first assessment of risk, is not a priority for the intelligence agencies. Inspectors must rely on their experience in spotting anomalies--a company that claims to be exporting pineapples from Iceland, for example.

Second, determined terrorists can easily take advantage of the knowledge that customs inspectors routinely designate certain shipments as low risk. A container frequently makes 10 or more stops between its factory of origin and the vessel carrying it to American shores. Many of the way stations are in poorly policed parts of the world. Because name-brand companies like Wal-Mart and General Motors are widely known to be considered low-risk, terrorists need only to stake out their shipment routes and exploit the weakest points to introduce a weapon of mass destruction. A terrorist cell posing as a legal shipping company for more than two years, or a terrorist truck driver hauling goods from a well-known shipper, can also be confident of being perceived as low risk.

So what needs to be done? A pilot project under way in Hong Kong, the world's largest container port along with Singapore, offers one piece of a potential solution. At an estimated cost of $7 per container, new technology can photograph the box's exterior, screen for radioactive material, and collect a gamma-ray image of a box's contents while the truck on which it is carried moves at 10 miles per hour.

Terrorists can defeat radiation sensors by shielding a dirty bomb with dense materials like lead. But by combining those sensors with gamma ray images, the Hong Kong system allows inspectors to sound the alarm on suspiciously dense objects. Inspectors would need to analyze enough of the scans--perhaps 20 percent to 30 percent--to convince terrorists that there is a good chance that an indistinct image will lead a container's contents to be sent for more reliable X-ray or manual examinations. Images of container contents would then be reviewed remotely by inspectors inside the United States who are trained to spot possible nuclear weapons.

If terrorists were to succeed in shipping a dirty bomb, for example, the database of these images could serve as a kind of black box--an invaluable forensic tool in the effort to identify how and where security was breached. That information could help prevent politicians from reacting spasmodically and freezing the entire container system after an attack.

Such a program could significantly reduce the likelihood that terrorists will smuggle plutonium or a dirty bomb through American ports. But it still would not stop a terrorist from importing highly enriched uranium, which can be used to construct a nuclear weapon. Lengthening the time that a container is screened for radiation would help, and this could be done without increasing waiting times if additional monitors were added to the Hong Kong system near the gate where the trucks must already stop for driver identification checks. Better still would be for the Department of Homeland Security to make the development of new technology that can recognize the unique signature of highly enriched uranium an urgent priority.

Finally, we must find ways to ensure that terrorists do not breach containers before shipments arrive at loading ports. Sensors should be installed inside containers in order to track their movements, detect any infiltration and discern the presence of radioactive material. Where boxes are loaded, certified independent inspectors should verify that companies have followed adequate protocols to ensure that legitimate and authorized goods are being shipped.

Taken together, these recommendations will require new investments and an extraordinary degree of international cooperation. But increased container security will not only help the United States prevent terrorism, it will also help all countries reduce theft, stop the smuggling of drugs and humans, crack down on tariff evasion and improve export controls. What's more, such a program would require an investment of just one one-hundredth of the capital that could be lost if we shut down the global container shipping system after an attack.

Container security is a complex problem with enormous stakes. American officials insist that existing programs have matters well in hand. But we cannot afford to take these perky reassurances at face value while the same officials fail to embrace promising initiatives like the Hong Kong pilot project.

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.

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.