The winter-safe deterrence debate

The status quo of large nuclear arsenals risks global catastrophe so severe that human civilization may never recover. If we care about the survival of human civilization, then we should seek solutions to make sure such a catastrophe never occurs. This is my starting point for exploring the potential for winter-safe deterrence. Perhaps, upon closer inspection, winter-safe deterrence will prove infeasible. But I do believe it is worth closer inspection. To that effect, I welcome this roundtable discussion and the broader conversation that my research has sparked.

I have defined winter-safe deterrence as military force capable of meeting the deterrence goals of today’s nuclear-armed states without risking catastrophic nuclear winter. Winter-safe deterrence recognizes two basic issues: first, large nuclear arsenals pose a devastating catastrophic risk; and second, nuclear-armed states may refuse to relinquish almost the entirety of their nuclear arsenals unless their deterrence goals are met through other means. Winter-safe deterrence thus aims to make the world safer given the politics of deterrence.

Personally, I would prefer that today’s nuclear-armed states simply decide that they no longer need deterrence based on the threat of massive destruction. Such destruction is immoral and against the spirit of international humanitarian law. To that effect, we should seek solutions that reduce the demand for this sort of deterrence, for example by improving relations between nuclear-armed states or by stigmatizing this deterrence. The ongoing initiative on the humanitarian impacts of nuclear weapons is enhancing precisely this stigma. I am proud to support the initiative. It is a first-best solution to nuclear war risk.

Winter-safe deterrence is a second-best solution because it avoids global catastrophe while leaving intact deterrence based on massive destruction. It is no surprise that winter-safe deterrence is controversial, because it forces us to consider which devastating weapons we would like militaries to have. This is a repugnant task. I assure you I take no joy in it. But if this task could prevent a major global catastrophe, then it is an important task to pursue.

In my research, I attempted an initial analysis of winter-safe deterrence. I do not claim to have any final answers, and I explicitly discourage governments from pursuing winter-safe deterrence until more thorough analysis has been conducted. The issues are just too complex for one research paper. While I could have done more research on my own before publishing, I decided that progress could be better made through open discussion. That said, I was cognizant of the risks that mere publication could pose, to the point that I even considered censoring myself. I am thus sympathetic to Brett Edwards’s thoughtful comments on the risks of discussing these ideas. He raises important issues on when international security policy research is too risky to publish. In this instance, I believe it would have been too risky not to publish the research, risking the possibility that the status quo would lead to global catastrophe.

My research considered a sizable list of weapons: small nuclear arsenals, conventional military force, conventional prompt global strike, neutron bombs, biological and chemical weapons, cyber weapons, and electromagnetic weapons. Perhaps there are other weapons also worth considering as replacements for deterrence with large nuclear arsenals; I would welcome any suggestions. I further considered these weapons for two types of destruction: destruction to infrastructure and destruction to human bodies. For humanitarian reasons, I hope that deterrence can succeed with threats to infrastructure alone. I do not know if it can, and would welcome any thoughts on that score, also.

Much of the conversation about winter-safe deterrence has focused on a hypothetical decision between deterrence with nuclear weapons and deterrence with non-contagious biological weapons (NCBWs). I regret that the conversation has been framed in this way. Winter-safe deterrence does not require picking one weapon over another. To the contrary, it can be achieved via combinations of weapons, including small nuclear arsenals. But my suggestion of some constructive role for NCBWs has been controversial, and I am glad for this to be debated.

Gregory Koblentz, Martin Furmanski, and Sonia Ben Ouagrham-Gormley all argue that NCBWs are not effective deterrents because their effects are too unpredictable and too easy to defend against, among other reasons. In short, they cannot reliably cause enough harm in counterattack. These points are well taken. The biggest question they raise in my mind is whether these technological shortcomings of NCBWs may be altered by technological advance, making them more suited for deterrence. Given advances in biotechnology, I hesitate to place bounds on what may be possible. I would be interested in further comments on this.

Ben Ouagrham-Gormley says something that catches my eye: “Non-contagious does not mean less lethal.” I am surprised to read this. It is my understanding that NCBWs can only kill people within the area in which they are released, whereas contagious biological weapons can spread, potentially even killing people worldwide. Could NCBWs spread as widely? If not, then how could NCBWs be as lethal?

Another point I am left unclear on is the proliferation risk posed by NCBWs. On one hand, Gigi Kwik Gronvall writes that “biological weapons development is within the technical capability of most countries,” suggesting a large proliferation risk. On the other hand, Ben Ouagrham-Gormley describes how countries and nonstate actors have repeatedly tried and failed to develop biological weapons, suggesting a small proliferation risk, or perhaps even none at all. I am unsure how to resolve this apparent conflict.

Gronvall’s comments on the international bans on biological weapons raise a difficult issue. If NCBW deterrence were technologically feasible, pursuing it could significantly harm the international treaty system. However, it could also help avoid global catastrophe from nuclear war. I hope we never have to make such a difficult choice, but if I had to choose, I would choose to avoid global catastrophe. That is, unless harming the international treaty system could itself cause global catastrophe (and perhaps it could), I would favor accepting this harm to avoid global catastrophe from nuclear war. When it comes to humanity’s long-term survival, the stakes are simply too high not to make hard choices.

But we should hope that this is a false choice. We should hope that other options exist such that we can avoid global catastrophe from nuclear war without harm to the international treaty system.

In closing, I thank the contributors to this roundtable for their thoughtful and constructive comments and look forward to continuing the discussion.

In his article “Deterrence, without nuclear winter,” Seth Baum argues that the greatest danger associated with current nuclear stockpiles is that nuclear winter will inevitably follow a nuclear strike and “threaten the whole of humanity.” To avoid such a catastrophic outcome, and thus promote drastic reductions in nuclear weapons, Baum proposes that nuclear states consider alternative weapons that would at once meet their deterrence objectives and preserve humanity from the devastating effects of a nuclear winter. Baum identifies five qualities that such ideal alternative weapons should possess: They should be “politically acceptable,” “not pose a significant proliferation risk,” not “destabilize the international system,” and possess a deterrent value while being “affordable and technologically feasible.” Baum concludes that “non-contagious biological weapons” possess such qualities and would constitute a “good” alternative to nuclear weapons.

I suspect that most nonproliferation analysts—particularly bioweapons experts— have found this proposition to be shortsighted. Baum’s suggestion simply redounds to advocating the violation of the Biological Weapons Convention (BWC)—a nonproliferation treaty that bans the development, production, and stockpiling of biological weapons. The article also ignores historical realities that are important to highlight because they demonstrate that biological weapons possess none of the attributes that Baum lists as essential for an alternative to nuclear weapons.

Among the nine nuclear weapons states—the United States, the United Kingdom, Russia, France, China, India, Pakistan, North Korea, and Israel—all but one (Israel, which has not openly declared its nuclear state status) have signed the BWC. Under the treaty, states agreed to destroy their bioweapons arsenals and refrain from developing, producing, and stockpiling bioweapons. Therefore Baum’s suggestions to promote nuclear disarmament by nudging nuclear states toward bioweapons development is akin to erasing over 40 years of international negotiations and achievements, the greatest of which was the development of an international norm against the development and use of biological weapons. In addition, if powerful states such as Russia and the United States were to resume their past bioweapons programs, they would not only place other nations at a disadvantage due to their lack of accumulated expertise in the field, but this would also have a chilling effect on all types of nonproliferation efforts, including nuclear disarmament. Why would North Korea renounce nuclear weapons when they could use them to counter the nuclear or bioweapons threat from more powerful states? Baum’s proposal is neither politically acceptable nor strategically advisable, while it also carries significant proliferation risks.

In his article, Baum puts the emphasis on “non-contagious biological weapons,” presumably because if these weapons cause non-contagious diseases, their effects would be more limited, making them somehow more acceptable. But the BWC makes no distinction between contagious and non-contagious bioweapons. All bioweapons are banned under the treaty. None is more acceptable than the other. Besides, historically most state and non-state bioweapons programs have focused on agents that do not cause contagious diseases, such as Bacillus anthracis (anthrax) and botulinum toxin. Very few programs have actually worked on contagious agents such as the smallpox virus. Non-contagious does not mean less lethal.

Further, biological weapons are poor deterrents. In addition to the fact that states can protect their populations beforehand, and in some cases even after an attack, depending on the agent used and the length of the incubation period, biological weapons do not guarantee a certain level of predictable destruction as nuclear weapons do. They are sensitive to light and weather conditions, making their use less effective during the day, when ultraviolet light can destroy the agents, or in windy conditions, when agents can inadvertently disseminate over unintended populations. Changes in air currents within cities and over variable terrain make it difficult to achieve accurate targeting. Their effects can also be mitigated by individual immune responses. Because of their sensitivity to environmental conditions, biological weapons are also difficult to deploy, making their use for a second strike problematic.

Historically, because of their unpredictability and the uncertainty of their outcomes, biological weapons were never fully integrated in US military doctrine. In the Soviet Union, the military also viewed bioweapons as unreliable, due to the difficulty of controlling their dispersion and the possible risks of infecting Soviet troops. Attempts by Soviet scientists to develop new biological agents, unknown in nature, which the enemy could not protect against, lasted about 20 years and did not go beyond the exploratory and research and development phases. Furthermore, both the United States and Soviet Union struggled to design effective missile systems for the delivery of these weapons. The US program did not produce a dedicated bioweapons cruise missile, and the Soviets could not solve technical difficulties associated with the development of a ballistic missile warhead that could effectively protect fragile bioagents against the stress of re-entry.

These challenges underscore my final point: Bioweapons are technically complex and can be very expensive. Their complexity derives from their reliance on living microorganisms that are highly sensitive to their environmental and handling conditions. Their behavior throughout the development process is unpredictable, which—as past state and terrorist programs show—causes many failures and delays in program advancement. Furthermore, the stages of a bioweapons lifecycle—research, development, production, scale-up, weaponization, and testing—are highly interdependent, and the successful passage from one stage to the next requires organizational and managerial conditions that promote coordination, cooperation, and information exchange among the various teams of experts involved. Such conditions are particularly difficult to achieve. As a result, most past state and non-state bioweapons programs have been unsuccessful at reaching their goals. The Soviet Union, which had the longest-running and largest program, spent an estimated $35 billion over the last 20 years of the program’s life but was unable to develop the new agents that it aimed to produce. The US program cost about $700 million over 27 years without producing a weapon that satisfied military requirements. Iraq spent over $80 million during the last five years of its program but was only able to produce ineffective weapons that would have destroyed most of the agents they contained upon impact. Finally, South Africa and the Japanese terrorist group Aum Shinrikyo spent about $30 million and $10 million respectively, but failed at all stages in a futile quest for bioweapons. Thus, bioweapons are hardly affordable, and their technical feasibility is constrained by a host of factors, of which I have mentioned only a few.

In short, bioweapons are not an alternative to nuclear weapons. Proposing to sacrifice the biological nonproliferation regime to ensure nuclear disarmament is simply shortsighted.

Seth Baum’s recent column, which called for legitimizing non-contagious biological weapons to replace the deterrent function of nuclear weapons, is problematic for me on a number of levels, but in this essay I will address only one: Would biological weapons be effective as weapons of deterrence, as potential replacements for some of the existing or future nuclear weapons?

The terrible destructive power of nuclear weapons is obvious: Hiroshima and Nagasaki demonstrated the power of first-generation fission warheads, and then, in the mid-20^th century, atmospheric testing showed the even more awesome potential of augmented fission and true thermonuclear warheads, which can be tens and hundreds of times more powerful. Nuclear weapons can be delivered by a variety of systems, primitive or sophisticated, and are effective in any environment or weather, against essentially any target: cities, military bases, hardened underground bunkers, and mobile military assets such as naval battle groups.

Defenses against nuclear weapons are ineffective. The heat, blast, and ionizing radiation of nuclear explosions can only be survived in hardened underground facilities, and then only if those facilities are not specifically targeted. Mediation of radioactive fallout damage is localized and feeble at best. There is no way of reversing or ameliorating the biological and physical damage after the attack has occurred. The sole defense against nuclear weapon attack is total interdiction of its delivery systems, a goal that may be unattainable when a single failure results in unacceptable death and destruction.

In contrast, the effects of biological weapons are speculative and unproven. The alarming, well publicized models of the dire consequences of bioweapon attacks, resulting in mass casualties, are based on a number of important but undisclosed technical assumptions and typically portray a “most damaging case” scenario. While this type of estimation is prudent in making risk assessments, it has also been, historically, self-serving to those persons and institutions making the estimates, because careers and appropriations are dependent on convincing scientifically unsophisticated military and political authorities of the potential danger of biological weapons. When one examines the actual constraints of field use of biological weapons, as discovered during the US offensive bioweapons program, which lasted from 1942 to 1969, one discovers fundamental limitations.

Biological weapons potentially useful as strategic deterrents would be delivered by wide-area aerosols. The effectiveness of bioweapon aerosols is profoundly influenced not only by the agent preparation and delivery system, but also by a large number of independent factors, such as time of day, temperature, humidity, local landforms and vegetation, degree and type of urban development, atmospheric temperature gradients, and wind speed and direction. Each of these compounding variables can influence the ultimate effectiveness by several orders of magnitude, so that unfavorability of even a few variables will render an aerosol attack ineffective. A deterrent weapon must offer the assurance of an immediate, effective retaliatory attack under conditions not of the defending nation’s choosing. Biological weapons cannot give this assurance.

Real-world biological targets offer considerable resistance to bioweapon effects, when compared to field tests on animals in cages. The modern filtration in air-handling systems in typical late 20th- and 21st-century buildings and vehicles significantly reduces the effectiveness of biological aerosols. Moreover, bioweapon agents are, after all, biological, and show biological frailty. They are exquisitely vulnerable to industrial type air pollution, an effect noted by United Kingdom investigators at Porton Down, when mid-20th century England was still burning soft coal. Much of China and many Asian and other cities in the developing world today would be similarly resistant to an aerosol bioweapon attack. These fundamental limitations on the practical employment of biological weapons were well known on an operational level during the US offensive bioweapon program, and are responsible for the distinct lack of enthusiasm for biological weapons by any branch of the US armed forces, except for the sponsoring Chemical Corps. Soldiers require weapons that will function as expected in the environment in which they find themselves fighting, when they are wanted and needed.  Biological weapons cannot meet this requirement.

Biological weapons are vulnerable to both pre-attack and post-attack defenses. Preemptive immunization would nullify the deterrent effect of a biological agent, and this has already been done by the US military in the case of anthrax and smallpox. In a true threat scenario, or to nullify another nation’s deterrent, mass immunization of the entire population could be undertaken: The US Strategic National Stockpile was created with this in mind. Such emergency mass immunization programs have been undertaken in non bioweapon-threat scenarios: The ill-fated 1976 swine flu immunization program immunized 40 million people in three months.

Biological weapon effects can be nullified or mitigated after the attack with post-exposure treatment. This had been evaluated experimentally in humans during the US offensive bioweapon program, but was most dramatically demonstrated in the 2001 postal anthrax attacks. At the Senate office building the threat was immediately recognized, and exposed personnel were given post-exposure antibiotics immediately. No cases occurred in that cohort. At two postal centers, the exposure was not immediately appreciated, and seven unexpected symptomatic inhalation cases developed. These first cases appeared in personnel who worked closest to the automated letter-handling machines that generated the aerosols, and who therefore received the highest dose. Upon recognition of the postal center exposures, all potentially exposed employees were put on post-exposure antibiotics. Only two of the seven symptomatic postal cases died, far less than the 90 percent fatality rate predicted before the experience with post-exposure antimicrobial therapy. Quite remarkably, no further cases appeared among postal personnel after the institution of post-exposure antimicrobial therapy, even though the 1979 Sverdlovsk anthrax accident in the Soviet Union and animal studies predicted new cases would continue to appear for 60 to 90 days.  Post-exposure therapy truncated the attack effects as soon as it was recognized.

To be a credible strategic deterrent, a weapon needs to offer assured unacceptable damage when used in retaliation against an enemy’s attack. Nuclear weapons are credible. Biological weapons, not so much.

In reading the initial Twitter response of academics and nongovernmental organizations to Seth Baum’s recent article in Contemporary Security Policy, "Winter-safe deterrence: The risk of nuclear winter and its challenge to deterrence," one would have been forgiven for assuming that the paper was advocating the use of non-contagious biological weapons as an alternative to nuclear deterrence in a way that was entirely uncritical. However, this is simply not the case. While the article does not provide in-depth analysis of the broader implications of Baum's argument, several of the themes outlined in recent critiques are at least partially reflected in his analysis. This includes for example the idea that the "Biological and Chemical Weapons Conventions must be considered among the greatest successes of the international community," and the caveat that "[m]any people would probably rather not even consider rescinding these conventions to re-proliferate these weapons, as well as the potential proliferation risks of such weapons." The paper is then, a provocative thought experiment that considers a hypothetical approach to reducing the size of nuclear arsenals, rather than a polemic against biological weapon prohibition. It involves describing a situation of such devastating human consequence that even the most morally repugnant of acts might become justifiable.

While it is tempting to engage in a more technical critique of assertions that are made about biological weapons in this article, I will leave this to colleagues with greater relevant expertise in this area. Instead, I want to draw attention to the almost allergic response of some commentators to Baum’s article, and consider its meaning and potential implications. The first key question one must ask is why such criticism has been forthcoming. A key reason: The paper is incredibly alien to those currently working in biological weapon control. This is because the paper is not motivated by the goal of ensuring the continued prohibition of biological weapons. Instead, the article provides a potential justification for developing and using such weapons. The article also places little emphasis on the benefits of the comprehensiveness of the international prohibition laid out within the 1972 Biological Weapons Convention. This convention prohibits the development, production, retention, stockpiling and use of such weapons under any circumstances. Any argument for "roll-back" within this treaty could also have implications for those working on sister treaty systems associated with the Conference on Disarmament. 

The unusual nature of the argument should not automatically invalidate the findings of the paper, but it does mean that the author would have to work hard to support such tentative assertions for them to be generally convincing. Such work would also likely have to go well beyond the scope of a single paper. If the author were to take up such a challenge, however, it would be entirely antithetical to the majority of academic and nongovernmental projects I am familiar with. From my perspective, the only potential value of such a project would be that it continued to cause other experts to recount the arguments against biological weapons and to explain why bioweapons cannot effectively replace nuclear weapons for strategic deterrence purposes.

I don't think Baum’s original motivation was to encourage a discussion about the allure of biological deterrents. Instead, his treatment of biological weapon norm was just collateral damage in his attempt to address the issue of winter-safe deterrence.  As stated above, while this is perhaps a questionable approach academically, it does not mean that the paper should not have been published in a peer reviewed academic paper such as Contemporary Security Policy. However, I do draw the line in at the appearance of these arguments, in a largely unqualified form, in a feature piece for The Bulletin. This publication has a respected, public-facing, and humanitarian profile and addresses biological weapons as a core issue area. The organization has a responsibility to its readership to ensure that controversial arguments such as Baum’s are sign posted as such, at the point of publication.

It seems likely that this is somewhat of a one-off paper. However, if it becomes the norm that biological weapon concerns are viewed predominantly and uncritically through a nuclear security lens within this publication, then this will likely have implications in terms of who contributes as well as the readership in the future. It would behoove The Bulletin to review its policy in relation to future publications of this type, to ensure concerns are flagged before the article goes to press. This will allow for decisions to be taken on the best way to present the article, if it is to be published. Controversial thought exercises, which go against the prevailing wisdom in relevant arms control communities, should be labelled just that. This is not to discredit such work, but to provide non-experts with a sense of the articles’ broader context.

The second key question is the extent to which further discussion of Baum’s paper is of broader value. I do not believe Baum’s academic paper presents a convincing enough thesis to be a genuine challenge to the international status quo, nor do I expect to see his arguments made publicly elsewhere by other experts. However, the paper has motivated some scholars and nongovernmental organisations to reflect on the norm against biological weapons. This is important because the question of "why" biological weapons should be prohibited has often taken a back seat to the question of "how" biological weapons are prohibited. This is understandable, considering the recent history of biological weapons. For over a decade, concerns about sub-state and pariah-state terrorism have contributed to the further stigmatization of biological weapons in press and media coverage. However, as we have seen in Baum's article, the very same things which make such weapons abominable, may also contribute to their appeal.

To sum up, I think the following key issues are worth further discussion. First, in the absence of any prospect of scientifically sound risk-benefit analysis, what sense does it make to advocate pursuing alternative modes of deterrence? Second, does Baum’s line of reasoning appeal to those working in the field of nuclear security? And finally, how can we ensure that the "false allure" of biological weapon deterrence does not take hold in the minds of the public and military strategists?

A recent Bulletin column has suggested that non-contagious biological weapons may be a useful alternative to nuclear weapons as a deterrent, and could reduce the threat of nuclear devastation. While the United States may consider a variety of mechanisms toward a more stable deterrence strategy with fewer nuclear risks, biological weapons development will not be one of them. Doing so would violate US and international law and would be morally reprehensible. It would also leave the United States less secure.

There are multiple legal restrictions. The Biological Weapons Convention (BWC, formally titled the Convention on the Prohibition of the Development, Production, and Stockpiling of Bacteriological [Biological] and Toxin Weapons and on Their Destruction) is the first agreement among nations that declared an entire category of weapons to be off limits. It has been in force since 1975, and there are currently 170 states parties that have agreed not “to develop, produce, stockpile or otherwise acquire or retain:  Microbial or other biological agents, or toxins whatever their origin or method of production, of types and in quantities that have no justification for prophylactic, protective or other peaceful purposes; Weapons, equipment or means of delivery designed to use such agents or toxins for hostile purposes or in armed conflict.” The 1925 Geneva Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare also bans the use of biological weapons in warfare. Taking the ban on bioweapons one step further, UN Resolution 1540 (2004) prohibits nations from supporting non-state actors toward developing, acquiring, manufacturing, possessing, transporting, transferring or using nuclear, chemical, or biological weapons or their delivery systems.

Biological weapons development is within the technical capability of most countries, so a revocation of the bioweapons ban could lead to a rapid proliferation of highly dangerous weapons. Even non-contagious biological weapons have enormous lethal potential that could rival the use of nuclear weapons, and could, in the case of anthrax, make the attack area unusable for a long time. The results of nation-state sponsored tests—back in the days before the BWC, and before the US renounced the development and use of biological weapons—demonstrate this. In 1968, a US military exercise took place 1,000 miles south of Hawaii, where hundreds of rhesus monkeys were loaded onto barges and exposed to aerosolized anthrax released from a Marine Phantom jet. Monkeys 50 miles downwind died of anthrax. In 1942, the United Kingdom tested bombs filled with anthrax spores on Gruinard Island, off the Scotland mainland, which left it uninhabitable for 48 years, until it was decontaminated at great expense.  

Instead of pursuing a weapons class that the international community has decided is off the table—a decision that has saved lives—the US government should continue what it is doing: working towards strengthening the BWC and rallying international partners to diminish the threat of sub-state actors or even individuals from pursuing biological weapons. While it would be a mistake to discount the technical skill, biological knowledge, and manufacturing technologies that were utilized in offensive biological weapons development when it was legal in the 1960s, there are many more technologies and shortcuts that would be available to a modern-day bioweaponeer. One can easily imagine how modern biological advances could be used to make a biological weapon more lethal, or difficult to detect or treat. 

In short, the ban on biological weapons continues to be the best policy. It has worked well to reduce proliferation—though there have been violations, no nation state openly declares that it is developing a biological weapons capacity—and it promotes US security.

In his recent column, “Deterrence, without nuclear winter,” Seth Baum concludes that non-contagious biological weapons are one of two viable alternatives to replacing nuclear weapons in order to achieve what he calls “winter-safe deterrence.” He writes that non-contagious biological weapons “could work well if deterrence required threatening large human populations” without posing the risk of a global catastrophe like nuclear winter or a pandemic. Leaving aside the disturbing normative and legal implications of Baum’s proposal to start a global biological arms race, I will focus on the strategic logic underpinning his proposal to replace nuclear weapons with biological weapons. Baum’s conclusion is based on an uncritical acceptance of the long-standing myth that biological weapons are “the poor man’s atomic bomb.” This myth is based on the simplistic notion that because biological weapons could potentially cause mass casualties on par with those caused by nuclear weapons, these weapons should have similar political effects and implications for international security. Although biological and nuclear weapons are both considered weapons of mass destruction, biological weapons differ from nuclear weapons in three important ways that undermine the utility of biological weapons for deterrence: uncertainty of effects, availability of defenses, and the need for secrecy and surprise.

The first significant difference involves the level of uncertainty associated with the employment of these weapons. Nuclear weapons deliver instantaneous, overwhelming, and predictable levels of destruction. The effects of biological weapons, on the other hand, are delayed, variable, and difficult to predict due to their sensitivity to environmental conditions and the importance of pathogen-host interactions. In addition, the lack of operational experience with these weapons and the inability to simulate realistically their effects (short of massive human experimentation) impedes the ability of states to substantially reduce this level of uncertainty.

The second major difference between nuclear and biological weapons concerns the availability of defenses. There are no effective defenses against the effects of a nuclear attack. There are, however, a number of countermeasures that can be taken before, during, and after a biological attack that can mitigate the consequences of such an attack. Masks and filters can prevent exposure to biological agents. Biological weapons are also unique in that vaccines can be used to protect soldiers and civilians before an actual attack occurs. Because diseases have an incubation period of days to weeks, defenders have a window of opportunity to detect an attack using sensors and biosurveillance systems. Early detection can trigger the distribution of medical countermeasures to treat the victims of an attack and there are already vaccines and /or treatments available for the most lethal diseases such as anthrax, plague, smallpox, and tularemia. As a result, the effects of a biological attack are not absolute and incontestable; they can be mitigated and limited by a well-prepared defender. This possibility is likely to reduce the confidence of states in their ability to reliably inflict unacceptable damage against an adversary in a retaliatory strike. The full panoply of defenses need not be deployed constantly at full readiness because the very availability of these defenses may be sufficient to dissuade a state from calculating that it can inflict unacceptable damage. Although civilian populations will remain more vulnerable to biological weapons than will military forces, damage limitation remains a viable option for larger, more advanced states facing less sophisticated adversaries.

Third, biological weapons have limited value as strategic deterrents due to the need for states to shroud their biological weapons programs in strict secrecy. This need for secrecy is driven by normative, legal, and strategic considerations. In the strategic context, the availability of defenses against biological weapons places a premium on the attacker achieving surprise. This undermines the ability of a state to use biological weapons as a deterrent in two ways. First, the secrecy required to retain the element of surprise in a biological attack reduces a state’s ability to issue credible threats to inflict unacceptable damage against an adversary. To make a deterrent threat credible, a state would not only have to admit that it was violating international norms and laws but it would also have to reveal details about its offensive biological warfare capabilities such as the types of agents it has developed and their means of delivery. These revelations could reduce the effectiveness of these weapons by allowing the defender to mobilize appropriate countermeasures. In contrast, the superpowers flaunted their nuclear forces during the Cold War for deterrent purposes. They were able to do this because these demonstrations of their nuclear capabilities did not provide the other side with an improved means of defending against them. Second, secrecy is a flimsy means of protecting strategic forces designed for deterrence. Strategic forces that depend on secrecy for their protection are vulnerable to intelligence breakthroughs by an adversary. If a defender gained inside information about an attacker’s capabilities, it would be possible to develop and stockpile new pharmaceuticals, immunize the at-risk population, distribute protective masks and treatments, enhance public health surveillance, and take other precautions that could substantially mitigate the impact of a first-strike or retaliatory attack with biological weapons. Although such information is difficult to acquire, the cases of Soviet biologist Vladimir Pasechnik, former Soviet bioweapons program official Ken Alibek, and Iraqi weapons official Hussein Kamal attest to the risk posed by the defection of high-level government officials knowledgeable about their nation’s biological warfare programs.

A careful analysis of the technical and strategic aspects of biological weapons reveals that while biological weapons have the potential to inflict unacceptable damage against an adversary, they are unable to offer states an “assured” capability for doing so. This shortfall significantly undermines the suitability of biological weapons to serve as a strategic deterrent. Whatever the merits may be of pursuing “winter-safe deterrence,” promoting the discredited concept of biological weapons as a “poor man’s atomic bomb” is not an analytically defensible means of achieving that objective.