For decades the United States has sought international standards to ensure that nuclear facilities and materials are physically protected against theft and sabotage. On September 11, the need for such an initiative became strikingly apparent as analysts pondered the other possible targets of a terrorist attack. What would have been the loss of life if, for example, a hijacker had crashed a fuel-laden jetliner into a nuclear reactor, causing a meltdown and dispersing radioactive material?

Indeed, just days after the attacks, Mohamed ElBaradei, the head of the International Atomic Energy Agency (IAEA), made it clear that the attack had dramatic implications for the nuclear industry and for non-proliferation: “The tragic terrorist attacks on the United States were a wake-up call to us all. We cannot be complacent. We have to and will increase our efforts on all fronts—from combating illicit trafficking to ensuring the protection of nuclear materials—from nuclear installation design to withstand attacks to improving how we respond to nuclear emergencies.”

Spencer Abraham, the U.S. secretary of energy, appeared before the IAEA to urge “maintaining the highest levels of security over nuclear materials.” “We need to strengthen international commitments and cooperation on the physical protection of nuclear materials, particularly those that can readily be converted to weapons use,” he said.

If terrorists were willing to kill thousands of innocent people in suicidal attacks against buildings symbolizing America’s economic and military power, they would probably not hesitate to use truck bombs made of conventional explosives to attack nuclear reactors in order to create clouds of radioactivity like those produced by the 1986 disaster at Chernobyl. They would have little trouble acquiring anti-tank weapons that could blow up the heavy canisters in which radioactive spent fuel from nuclear reactors is transported through populated areas. It is even possible that they could acquire fissile material from one of the poorly guarded nuclear facilities around the world and find scientists willing to make nuclear weapons.

Current international agreements do not require that nuclear material and facilities in domestic use be guarded against thieves or saboteurs, including terrorists. This is a dangerous gap in the global barrier against proliferation. The IAEA has taken the first steps toward requiring measures to physically protect nuclear materials, but it is essential that this effort be pursued expeditiously and that countries take all reasonable steps to ensure that nuclear material is not part of the next terrorist attack.

The horrifying events of 11 September 2001 serve notice that civilization will confront severe challenges in the twenty-first century. As national security budgets expand in response, we should recognize that only a broad conception of security will be adequate to meet some of the threats that we may face. Biological security provides a powerful example. It must address both the challenge of biological weapons and that of infectious disease. The right approach should benefit public health even if major acts of biological terrorism never occur. Our thinking about biological security must transcend old misplaced analogies to nuclear and chemical security.

Nuclear security has been based on nonproliferation, deterrence, and defense, with intelligence woven throughout. Nonproliferation seeks to prevent the diversion of materials from civilian programs to military or terrorist weapons. Should nonproliferation fail, the United States relies on deterrence through the threat of retaliation. Defense, active or civil, has so far been less central.

Effective biological security requires a different mix. For all its challenges, nuclear nonproliferation is comparatively robust, in part because the production of weapons-usable uranium or plutonium provides a conspicuous bottleneck through which any nuclear program must pass, unless those materials are stolen. This is why preventing nuclear theft is such a high priority in the post-Cold War world. Biological agents

are easier to acquire. Most can be found in naturally occurring outbreaks. Weaponizing these agents has proved challenging for terrorist groups, but the Aum Shinrikyo's unsuccessful efforts to spray the anthrax organism throughout Tokyo in 1993 warned that attempted mass urban attacks were no longer in the realm of the fantastic.

The transfer of dangerous biological agents should be controlled where possible, and the spread of the technologies and personnel to weaponize them should be impeded. But any biological nonproliferation regime will necessarily be less robust than its nuclear counterpart, because the relevant materials, technologies, and knowledge are far more widespread.

Biological terrorism also challenges requirements for successful deterrence. Because some diseases incubate for a week or more, identifying the perpetrators of an attack may prove difficult. A terrorist group might even hope that its attack would go unrecognized; when followers of the Bhagwan Shree Rajneesh infected 750 Oregonians with salmonella in 1984, it took over a year before the infection was determined to have been intentional. Finally, as with any form of terrorism, some groups may simply be unconcerned about retaliation.

In the face of these difficulties, good intelligence is all the more important. Warning and prevention are preferable to coping with the consequences of an attack, but we must also be ready should an attack occur. This requires that greater emphasis be placed on improving public health, a kind of homeland defense that is applicable to both unintentional and intentional disease outbreaks.

Because of disease incubation times, the first responders to a biological attack may well be health-care workers at hospitals and clinics rather than specialized units. The speed and effectiveness of a response will depend on disease surveillance: the recognition by health-care workers that certain illnesses appear unusual and the rapid notification of the proper authorities. Because incubation times often exceed international travel times, both domestic and international components are required. But the domestic component of disease surveillance in most nations, including the United States, is too weak, and international networks are inadequate. Donor nations need to increase support for these efforts. And there are many other needs, such as developing and stockpiling sufficient vaccines, antibiotics, or antivirals and otherwise preparing to meet the enormous challenges that would be posed by a major outbreak. It is time to quicken the pace of these efforts, to which departments of health are as central as departments of defense.

Disease surveillance and response are not nonproliferation measures, so cannot substitute for an effective verification regime under the Biological Weapons Convention. But biological security requires the developed world, especially the United States, to see that its ongoing self-interest is closely allied with sustainable public-health improvements in the developing world. And the explosion of biotechnology, with the weapons implications that follow from it, requires the scientific community to discuss its responsibilities in earnest.

STANFORD, Calif.- For the past seven years, the United States has been negotiating a verification protocol to the Biological Weapons Convention of 1972, hoping to put teeth into the convention's ban on biological weapons production. The Bush administration recently rejected the latest draft of the protocol, viewing it as irredeemably flawed. This is a good time to ask what a new American strategy should be for security against biological threats. It is difficult to predict the likelihood or scale of biological attack. The right policy will provide benefits whether or not an attack occurs.

The first step is conceptual: we must stop thinking about biological security in the way we think about nuclear security. Few aspects of the United States strategy for nuclear security carry over cleanly to the biological case. Security against nuclear attack has relied upon nonproliferation and deterrence, with comparatively little role, so far, for defense. Security against biological-weapons threats should lean primarily on defense.

Nonproliferation, for example, is far more difficult in the biological case. Biological agents are microscopic organisms that can be grown with equipment readily available all over the world -- although the resulting weapons have proved difficult for terrorists to master. Many of the organisms can be acquired during naturally occurring outbreaks. Controls remain valuable, but they will never play the central role that they do in nuclear security. And as biotechnology explodes in the coming decades, nonproliferation will face ever greater challenges.

Deterrence may likewise be of limited use in preventing attacks with biological weapons. While the use of battlefield biological weapons may be deterred by threats, biological terrorism could remain largely immune. The incubation times of most diseases -- for example, seven to 17 days for smallpox -- may lead terrorists to hope they can cover their tracks through covert releases of biological agents. Deterrence relies on the threat of punishment. An attacker who cannot be identified cannot be threatened.

When the Aum Shinrikyo cultists sprayed an anthrax organism in Tokyo -- they did so unsuccessfully several times before their deadly 1995 nerve-gas attack -- they made no announcements and the attacks went unnoticed. When followers of the Bhagwan Shree Rajneesh infected 750 Oregonians in 1984 with salmonella, it took over a year for the attack to be distinguished from a natural outbreak.

Rather than nonproliferation and deterrence, biological security must emphasize civil defense. Civil defense in the biological realm means improving the public health system. Most important, it requires improving disease surveillance. Unusual disease outbreaks must be recognized quickly, so that a rapid response is possible. Health care workers in clinics, hospitals and private practice must know how to identify such outbreaks and be ready and able to pass their information rapidly to city, state and national authorities.

This kind of preparedness would also help to prevent unintentional outbreaks of disease. Because infected passengers can travel the world in less time than it takes for a disease to incubate, it is crucial, for the national interest as well as for humanitarian reasons, to improve disease surveillance overseas. The United States welcomes 50 million visitors every year and imports $40 billion worth of food. Disease cannot be stopped at the border. The United States must act internationally as well as nationally.

Because biological security would offer protection against both natural and nefarious transmission of disease, a sound policy would directly benefit society even if no attack ever happened. Effective biological security requires that we fit the cure to the disease.

The official U.S. government policy is to maintain "calculated ambiguity" about whether the United States would retaliate with nuclear weapons in response to an adversary's use of chemical weapons (CW) or biological weapons (BW) against U.S. allies, U.S. armed forces overseas, or the U.S. homeland. Since the 1991 Gulf War, numerous civilian and military leaders have stated that the United States might use nuclear weapons in response to CW and BW threats or attacks, and some have even stated that the United States will use nuclear weapons in such circumstances. The central argument in my spring 2000 International Security article was that this policy has created a dangerous "commitment trap" problem.

The benefit of making such nuclear threats, whether stated ambiguously or clearly, is that they can increase an adversary's estimate of the probability that the U.S. president would order nuclear retaliation, which should therefore decrease the likelihood of chemical or biological weapons attacks. But there is a serious cost attached to this obvious benefit: If deterrence fails despite nuclear threats, the statements will also increase the likelihood that the United States will actually use nuclear weapons, because the president's personal and the U.S. government's institutional reputations for following through on threats would be perceived to be at stake.

I argued that current U.S. nuclear doctrine has therefore created a subtle dilemma that has not been recognized, much less debated, in both policy and academic circles: Is the improvement in the U.S. ability to deter CW and BW threats worth the increased likelihood of a U.S. nuclear response if deterrence fails?

A joint Stanford University-Lawrence Livermore National Laboratory team of scientists, nuclear engineers and arms control experts has concluded in a new study that North Korea's compliance with the 1994 Agreed Framework can be verified to a satisfactory degree of accuracy. Special effort, however, will be needed from the International Atomic Energy Agency (IAEA), as well as support from the US, the Republic of Korea (ROK), Japan and perhaps other countries. Most importantly, cooperation and openness from North Korea are essential.

The 1994 Agreed Framework (AF) between the United States and the Democratic People's Republic of Korea (DPRK) has become the centerpiece of recent US efforts to reduce the threat of conflict on the Korean peninsula. Under the AF, the US and its allies (mainly South Korea) will provide the DPRK with two large nuclear-power reactors and other benefits such as annual shipments of fuel oil for the generation of electricity until the nuclear-power reactors being built for that purpose are able to do so. In exchange the DPRK will declare how much nuclear weapon-usable material it has produced; identify, freeze, and eventually dismantle specified facilities for producing this material; and remain a party to the nuclear Non-Proliferation Treaty (NPT) and allow the implementation of its safeguards agreement.

The AF is now being carried out according to a complex and currently delayed schedule. Fuel oil shipments have been provided to the DPRK, the site for the two nuclear-power reactors has largely been prepared, and construction has begun on some components. The DPRK, for its part, has declared some nuclear weapon-usable material and has identified and frozen some facilities for producing this material.

As emphasized in President Bush's statement at the White House on March 7, 2001, verification is an essential part of any agreement with North Korea. How well can it be verified that the DPRK has no access to nuclear weapon-usable material? What is the potential impact of delays, disagreements, and lack of cooperation on verification? The United States and the international community must answer these questions if the nuclear-power reactor project is to proceed as planned.

The report analyzes in detail both the task of safeguarding the nuclear-power reactors to be provided and also that of dealing with known or suspected nuclear-materials production facilities in the DPRK. Scenarios governing both DPRK cooperation and possible non-cooperation, up to and including abrogation of the agreement are considered.

The challenges of verification examined in this report must be met if a necessary minimum of trust is to be established between the parties and the rewards of the agreement are to be realized. The authors believe that the challenges can be met under the conditions outlined in this report, but that special effort on all sides will be needed to meet them.

The break-up of the Soviet Union resulted in conditions that focused attention on the possible risk of "loose nukes."  But the risk from insecure nuclear materials is not limited to the former Soviet Union; there is a need to ensure adequate physical protection on a global basis.