By Karl Mueller for Stimson Center
14 November 2014
Do nuclear and space deterrence have more in common with each other than other versions of the theory? Karl Mueller doesn’t think so. The contrasts between these two particular forms of deterrence are far more pronounced and instructive than their similarities.
This article was originally published by the Stimson Center on 27 September 2013 as part of an essay collection entitled "Anti-satellite Weapons, Deterrence and Sino-American Space Relations".
In his introductory essay to this volume, Michael Krepon surveys and compares nuclear deterrence to the related and still rather nascent policy arena of space deterrence. This chapter takes another look at space deterrence, approaching the comparison from a slightly different direction by focusing on theory and strategic principles while giving short shrift to the history of the policy-making in question that his chapter presents in detail.
The connections between space power and deterrence have been a matter of increasing interest in recent years as the United States has become more and more dependent on space systems to perform essential military functions, and as the rise of China has demonstrated that deterrence is central to national security policy in all ages, rather than being something that mostly mattered during the Cold War. As we think about these connections, it is natural to turn to nuclear deterrence in a search for useful analogies. The study of nuclear deterrence, embracing both theoretical and practical dimensions, has achieved the often elusive objective for a highly theoretical discipline of actually having been useful to policymakers.
Nuclear power is different from conventional power in important respects, and space power is different from terrestrial power. Does understanding nuclear deterrence, in particular, give us useful insights into deterrence in space? Or do nuclear and space deterrence have more in common with each other than they do with other varieties of deterrence? It would be nice if the answer were “yes” because decades of thinking very hard about nuclear deterrence has resulted in a well-developed body of theory about it,(2) although much of it has not been tested due to the absence of nuclear wars and the infrequency of deep nuclear crises. Even though we have seen no nuclear weapons fired in anger since 1945, deterrence is not mere guesswork: The absence of explosions does not indicate the absence of deterrence; it indicates the absence of deterrence failures.
This brief essay will argue, or at least assert, that it is important for anyone seeking to understand space deterrence to have a basic mastery of nuclear deterrence – indeed, anyone seriously interested in national security affairs at the level of relationships between major states ought to have a grasp of this now relatively neglected subject. There are noteworthy analogical nuggets to be found in such a comparison – some metaphorical, others more concrete. But in the end, nuclear deterrence and space deterrence differ in so many ways that the contrasts between them are far more pronounced, and more illuminating, than the characteristics that they have in common.
Deterrence
It is not only natural but essential to begin by establishing what deterrence is and how it works in general. The term is often bandied about with limited regard for conceptual precision, and, even among those who do concern themselves with clearly defining deterrence, there is less consensus about what it does and does not comprise than one might expect. Search the political science literature for explicit and implicit definitions of deterrence – if one has nothing better to do – and one will find disagreements about whether it is proper to apply the deterrence label to threats of denial as well as punishment, to promises as well as threats, to wars being averted by external conditions or self-restraint as well as deliberate signaling by an opponent, to the non-occurrence of wars that no one was very interested in starting in the first place, to preventing wars before a crisis occurs, and even (though mostly in works of several decades past) whether there can be such a thing as non-nuclear deterrence.
Usually a broad definition of deterrence is most useful for scholarship, and even more so for policymakers who are interested in results more than debates about taxonomy. For the present discussion, it will suffice to say that deterrence refers to trying to cause someone not to do something (such as starting a war) by changing their expectations about the consequences of their potential actions (and also to the outcome of such efforts if they are successful). Deterrence is a subset of coercion,(3) and can (and should) be differentiated from actions that reduce or eliminate the adversary’s ability or opportunity to misbehave instead of deterring it from doing so; the latter is the domain of “brute” or “pure force,” destruction or unconditional appeasement.(4)
This is not the place for an extensive primer on deterrence, so I will settle for making four important points about the subject. First, and most fundamentally, deterrence is something that occurs in the mind of the enemy. It is a function of the opponent’s expectations, which in turn depend on their perceptions and beliefs; objective reality usually affects these, but when what is real diverges from what is perceived, it is the latter that matters. (In contrast, defense is what happens if deterrence fails, at which point objective reality takes over.) Thus, bluffs may deter but will not provide protection if they are called, while the opposite is true of defenses that the enemy does not know about. Similarly, escalation thresholds are what the actor responding to them thinks they are which may not align with the expectations of an adversary.(5)
Second, deterrence is about the relative attractiveness or unattractiveness of alternative courses of action. States do not go to war because they expect to win, they do so because they expect to be better off if they attack than if they do not. If the expected value of the status quo is very low (if the enemy “has nothing to lose”), even a very risky action may be preferable (picture Japan in 1941), while an actor who is well contented with his current situation may find even the prospect of cheap and easy victories to hold little appeal. For the deterrence practitioner this means it is always important to consider how the alternatives will stack up against each other in the opponent’s eyes, and to keep in mind that making the status quo look better can be just as useful for deterrence as making war look worse.(6)
This leads into the third point, which is that there are many ways to deter, since there are multiple approaches to making an opponent think that starting a war or escalating a conflict would be worse than not doing so. Prudent deterrers will look for opportunities to exploit across this range, and will be attentive to the risk that a threat or promise in one avenue will undermine deterrence efforts in another:(7)
Punitive deterrence involves increasing the expected costs of one or more potential outcomes of the action to be deterred. Examples range from retaliatory nuclear attacks to inflicting a lot of casualties on the battlefield to threats of economic or diplomatic punishment – including by third parties. The most potent punitive threat will be ones that apply whether or not the opponents’ action succeeds.
Deterrence by denial works by making the desired outcome of an action, such as victory in a war, appear less likely and some less appealing outcome look more likely. Decreasing your apparent vulnerability to an attack is a good way to discourage it, but some threats are harder to foil than others, and relatively weak deterrers may have little ability to threaten defeat or even frustration against a more powerful opponent.
Rewards and reassurance (positive deterrence if you prefer) seek to make aggression or escalation less attractive by making the status quo look more beneficial or less dangerous to the potential adversary. If the opponent expects that the result of restraint will simply be a war on less favorable terms later, there will be little incentive for restraint.
Unconditional measures of various sorts can also contribute to the prospects for deterrence, though strictly speaking they are not coercion. Destroying a key enemy military capability before it is used can make a threat less dire; at the other end of the spectrum, settling an existing dispute may eliminate the principal motive that might otherwise lead to war.
Finally, when moving from the theoretical plane to making strategy for the real world, talking about deterrence in general is rarely very useful, instead it is essential to specify whom you want to deter from doing what (and under what conditions). Even for the same opponent, the best approach for deterring it from taking action A may not be ideal, or even effective, for deterring it from closely related action B. Conversely, a strategy that is well suited to deterring one target from a particular form of misbehavior may be a very poor choice for deterring someone else from doing the same thing.
Nuclear Deterrence
With this last point firmly in mind, it is worth taking a moment to be clear about what the term “nuclear deterrence” means, which is not quite as simple an issue as one might assume. In everyday conversation, nuclear deterrence usually refers to using nuclear threats or nuclear weapons (which is more or less the same thing most of the time) as a deterrent tool. Thus, we might argue about whether nuclear deterrence can be relied upon in a particular case not only to deter an opponent from employing nuclear weapons but also to deter any number of non-nuclear actions such as invading a neighbor using conventional military forces. However, for the purposes of comparing nuclear and space deterrence, it will be more useful if we instead scope our consideration of nuclear deterrence based on what is being deterred rather than what is being used to do it: that is, to think about how the use of nuclear weapons has been and can be deterred, whether by threats of nuclear response or other means entirely, including but not limited to conventional military action.
Space Deterrence
The reason for framing nuclear deterrence as deterrence of nuclear use rather than deterrence by nuclear threat is that when we talk about space deterrence we almost always have in mind deterring attacks against satellites and related space systems, not the use of space capabilities for deterrent purposes, which is a vast and multifaceted subject given the variety of functions that space systems perform.(8) However, this is still quite vague by the standards of the “deterring whom from doing what?” criterion.
There are many ways to attack or interfere with satellite operations, ranging from the literally inoffensive (such as deception measures against imaging) through various flavors of jamming, dazzling and other non-kinetic attacks with either temporary or lasting effects, up to outright attacks by projectiles, directed energy weapons or other means to damage or destroy satellites. (Alternatively, targeting the ground segments of space systems may be an easier and more attractive option, but this largely falls outside of what we usually have in mind when discussing space deterrence, since deterring such actions is essentially the same as dealing with threats to other terrestrial targets.) For the purposes of this discussion, we will focus on the high end of the scale, leaving aside low-grade interference with satellites or the services they provide; also omitted will be any serious consideration of cyberattacks directed against space-related systems, since deterring such actions involves a broad topic of deterrence analysis unto itself.(9) Thus, references to “space weapons” in the pages that follow can be read as synonymous with “anti-satellite (ASAT) weapons,” always keeping in mind that among the ranks of potential ASATs are a variety of weapons and tools that are primarily intended for other purposes, from mid-course ballistic missile defenses to manned spacecraft.(10)
The issue of who might need deterring and under what circumstances often receives less attention than it merits. It is easy to list a wide variety of potential adversaries who might be interested in launching ASAT attacks against the United States or its allies if they had the capability to do so, but in practice there is a relatively limited set of opponents and scenarios that appear to be plausible foci for space deterrence concern rather than merely being imaginable.
It is worth noting that in virtually every conflict the United States is vulnerable to at-tack in many forms and many places that are not actually carried out, either because enemies lack the inclination to do so (before or after taking the likely consequences into account), because they lack the imagination to recognize the possibility, or be-cause they have more attractive things to do with their capabilities. Although satellites are intrinsically vulnerable to attack in absolute terms, thanks to orbital mechanics and the limited potential for concealment in space, on the whole they tend to be relatively challenging targets for physical attack when compared with the relevant alter-natives. The most economically valuable satellites, and many of the most militarily important ones, operate in high orbits that make them much more difficult to attack than their counterparts in low Earth orbit (LEO). Moreover, enemies interested in inflicting economic damage or psychological trauma on the United States will find many easier ways to do at least as much harm by striking terrestrial targets. This is likely to be less true for attacks seeking to cause military damage or disruption, but even there, striking at the ground segments of space systems, or interfering with their effective operation through terrestrial jamming or other means, will often be easier than attacking the satellites themselves in orbit.
Yet there are conditions under which attacking US satellites might indeed appear to be sound policy for an adversary, even though these are likely to be more limited than is often supposed. Three sets of circumstances loom especially large. The first is situations in which an ASAT attack, or a series of them, would offer a substantial military payoff in a situation of ongoing or imminent crisis or conflict. This would be most likely if attacking satellites were a way to exploit key vulnerabilities of US military power; how substantial the potential for that to be the case in the future will depend greatly on the ways in which the United States carries out the various elements of its military transformation plans over the coming generation, in addition to how well it deals with the challenges of satellite protection per se. Achieving such effects on a large scale would require considerable ASAT capabilities, and thus would likely be the purview of relatively major powers.(11)
Second, ASAT attacks promising more limited benefits might be attractive in cases where ASAT capabilities had already been built – perhaps only as a deterrent to US ASAT attacks – and a conflict or crisis subsequently broke out in which it appeared likely that the systems eventually would be destroyed or rendered ineffective: a “use it or lose it” situation. In a conflict in which the adversary faced the prospect of conquest or regime change being imposed by the United States, of course, every weapon would fall into the “use it or lose it” category, and high stakes (and possibly psychological desperation) could be expected to make deterrence particularly difficult.
Third, ASAT attacks could be appealing by offering a way to attack the United States or its allies (or to send a powerful coercive signal about one’s willingness to use force) while limiting escalation risks, making retaliation problematic or allowing the state launching them to maintain the moral high ground. Damaging or destroying satellites could cause considerable economic or perhaps military damage without killing many people – depending on the nature of the attack it is conceivable there would be no immediate loss of life – and without attacking the adversary’s homeland. Among the possibilities, a high-altitude nuclear detonation could offer a way to employ nuclear weapons without causing mass destruction, in response to which the likelihood of US nuclear retaliation might appear to be quite low.
Similarities: The Power of Rocket Science
Why should we expect nuclear and space deterrence, and nuclear and space power more generally, to have a lot in common a quarter century after the end of the Cold War? (12) That the association seems intuitively natural, at least at first, would seem to have much to do with the technologies that underpin these policy realms.
Perhaps the most obvious nuclear-space parallel is that power and deterrence in both cases are conspicuously and intimately connected to space age (and information age) physics. This matters on at least two levels. One is that to participate usefully in discussions of either nuclear or space deterrence it is necessary to have a basic grasp of the science involved in the field, as well as an understanding of deterrence and of the larger strategic context. This does not mean that one has to be able to design an atomic bomb, a missile or a satellite to discuss them intelligently, or that having deep expertise in the science or engineering of either field necessarily will make one more astute about related policy issues than someone with more rudimentary knowledge of the subject – Albert Einstein was far from prescient about the realities of a nuclear-armed world. But just as knowing the difference between a bomber and a ballistic missile or why multiple independently targetable reentry vehicles (MIRVs) mattered was indispensable for thinking about nuclear deterrence in the Cold War, and understanding the differences between nuclear and chemical weapons is essential to discussing weapons of mass destruction intelligently today, wrestling with issues of space deterrence requires knowing something about orbits and gravity wells and the functions that satellites perform.
This isn’t really a problem – or rather it shouldn’t be. A bright undergraduate can learn enough about nuclear weapons and strategy in a few hours to opine intelligently about nuclear deterrence. Space is somewhat more complicated, but the intellectual entry costs are also far from prohibitive.(13) Yet military space power has become – indeed it has always been – primarily the preserve of a relatively small group of specialists, both within the US Air Force and other armed services and in the broader policy-making and policy-assessing world. A variety of factors contribute to this, some relate to the domain knowledge being fairly arcane, some are sociological and all are reinforced by the secrecy that surrounds many national security space activities and programs, particularly the most advanced and expensive ones. Something analogous is true of nuclear strategy and policy, particularly since the end of the Cold War when the use of nuclear weapons seemed to become a far more remote possibility and interest in nuclear arms control diminished accordingly – as did the attention devoted to the subject in staff and war colleges, civilian universities and most other places where is-sues of nuclear policy were once matters of mainstream concern and debate.(14)
In practice, the peripheralization and sometimes isolation of the communities of nuclear experts and space experts can have potentially serious consequences. It can narrow or stifle debate and innovation (although this is not inevitable – isolation can also create space for innovation by excluding people who would interfere with it) and may facilitate or perpetuate dysfunctional processes or policies. More dangerously, if nuclear or space strategy becomes a domain disconnected from the broader national security community, either inside or outside of government, it can leave the United States ill-prepared to deal with crises and other events involving these capabilities by making them less familiar to non-specialist military and civilian leaders. Coming to grips with the realities of space power and space deterrence, as with the corresponding nuclear issues, is not something to undertake once a crisis in which they loom large is already underway.
Proliferation
Nuclear and military space capabilities both began as the exclusive domain of the superpowers, and subsequently have spread gradually to other countries. Originally the entry costs of nuclear weapons and space programs were astronomical. Beyond the United States and the Soviet Union, many of the largest and wealthiest major powers decided not to take on the expense and inconveniences associated with making the effort to join the nuclear club – and powers that did generally contented themselves with relatively small arsenals.
Over the past 50 years, the economic barriers to becoming a nuclear power have eroded to some degree. It is still no small matter to achieve entry into the nuclear club, but much of this difficulty is due to deliberate action to raise political and other obstacles to nuclear proliferation. As South Africa demonstrated in the 1980s, developing a basic atomic weapons capability has become something that virtually any sizable, sufficiently motivated state can achieve eventually. North Korea more recently drove this point home. That relatively little nuclear proliferation actually occurs reflects a dearth of countries that want the bomb more than a lack of countries’ abilities to acquire it.
The story is not terribly different in space. Here we are not thinking so much about the growing roster of states that have become spacefaring by owning their own satellites as about the slower but significant spread of space launch, ballistic missile and other capabilities that could be used as the basis for operational antisatellite capabilities.(15)
As with nuclear weapons, the entry costs are considerable, requiring the resources of a state rather than an eBay account and a credit card, but it is now a game in which states other than superpowers certainly can play.
There is also a clear parallel between the proliferation of nuclear and space capabilities on the political side: No state has ever developed nuclear weapons or substantial military space assets just for their cachet, but considerations of prestige can figure into such decisions to an important degree, as illustrated by the Cold War space and arms races between the United States and the USSR.16 This can matter to deterrence by, for example, leading governments to acquire or maintain destabilizing weapons for reasons other than their strategic utility, or contributing to provocative arms racing behavior.
These things being said, it is worth noting that there are important differences be-tween joining the nuclear and the military spacefaring clubs. One is that civil and national security space tends to be very intertwined on multiple levels, so states can find the need to contemplate issues of space power and space deterrence thrust upon them as a result of going into space for reasons that have little to do with military power. In contrast, while civil nuclear programs and nuclear weapons programs can certainly be related to each other, states do not, as a rule, stumble into becoming nuclear powers, 17 though they may well achieve that status without having fully thought through all of its implications.
Another contrast is that, so far, nuclear weapons have always remained in the clear possession of a single state, or at most a few states under a dual-key arrangement where the weapon belongs to one country but is based in, and perhaps delivered by, a system belonging to a close ally. For many space systems against which the United States might want to deter attack, things are not so simple. Satellite constellation may be owned by international consortia or multinational corporations, for example, and there might be many users of a single system, changing frequently as transponder leases change or new contracts are let for space-based services. This makes deterrence more complicated, though greater complexity doesn’t necessarily imply greater difficulty. For example, one argument in favor of US military use of non-US satellites for functions like communications is that an enemy might be reluctant to attack third-party satellites with a broad customer base in a situation where it would be willing to attack ones whose loss would hurt only the United States.
Crisis Stability
Of central importance to deterrence, more or less by definition, are issues of crisis stability.(17) When prospective combatants have strong incentives to strike first in a confrontation, because they would be much better off by doing so than if the opponent landed the first blow, deterrence becomes much more difficult than if there is little incentive for preemption. The same is true for decisions about whether to take escalatory action in a conflict already underway. Here, again, there are noteworthy parallels between nuclear and space deterrence. (There are important differences as well, and we will return to the subject of crisis stability in the next section.)
The two most important of these similarities both derive from the tendency for nuclear and ASAT attacks to be difficult to defend against. Defending against ASAT attacks tends to be hard because of physics and the geography of orbital space: Satellites are difficult, even often impossible, to conceal and difficult or costly to maneuver out of harm’s way. Defending against nuclear strikes can also be very hard, particularly when the weapons are delivered by ballistic missiles, but the fundamental problem with trying to intercept incoming nuclear warheads is that even defenses with a high success rate may be of little strategic value because a very small number of “leakers” can be sufficient to cause vast destruction. If an attacker has high confidence that an attack of either type will be at least operationally successful because defenses are not effective, deterrence efforts will need to focus on punishment and reward strategies because deterrence by denial will have little to offer. This is a problem that extends beyond the confines of crisis stability, but it can be especially acute in a crisis by creating powerful incentives for a first strike if war appears inevitable, or even merely likely. Moreover, when the stakes are high, making punitive threats (or reward offers) that are powerful enough to deter, absent being able to threaten an attacker with actual defeat, can be a very difficult strategic mountain to climb.
The second issue is closely related. Under conditions of real or perceived first-strike advantage, and with weapons for which tactical warning from detection to attack may be measured in minutes (or even less for some directed energy attacks or for attacks by prepositioned “space mines”), decision-making timelines are likely to be very com-pressed.(18) This can cause or contribute to a witch’s brew of pathological effects, limiting opportunities for communication and signaling between adversaries or mediation by third parties, constraining the collection and analysis of information and consideration of alternative options, even causing panic and other psychological problems for decision makers under intense pressure.(19)
It is important to qualify this discussion, however. While defense against nuclear and ASAT attacks tends to be difficult, the verb is intentionally tentative; the extent to which the tendency manifests itself in practice will depend on the weapons and defenses that the nations involved choose to deploy. Weapons that are vulnerable to at-tack will threaten crisis stability much more than ones that have a reasonable prospect of surviving an enemy first strike; weapons that are particularly or only vulnerable to surprise attack are likely to be especially destabilizing. Thus systems such as unhardened, MIRVed, land-based ballistic missiles or space-based ASAT laser weapons are crisis stability nightmares, combining offensive usefulness with great potential vulnerability that creates “use-it-or-lose-it” incentives for decision makers not to risk allowing a powerful adversary to strike first.
Environmental Effects
As a coda to close out this enumeration of parallels between the arenas of nuclear and space deterrence, it is also worth noting briefly the similarities among some of the potential environmental consequences of nuclear and space warfare. The physics of nuclear fallout and of orbital debris due to kinetic-energy ASAT attacks are entirely different, but from a policy perspective they have much in common. Both are potentially serious and, on a large enough scale, catastrophic contamination threats that originate as collateral effects of particular attack methodologies – or that can be generated deliberately as a means of inflicting additional harm on an enemy. Because their effects are essentially indiscriminate, affecting geographically vulnerable bystanders without regard for national borders, they magnify the extent to which deterring nuclear or space combat is a matter of concern to non-belligerents, and cast a long shadow over issues of weapon investment and testing.
At the extreme end of the scale, it is not unreasonable also to suggest that there is more than a passing resemblance between “nuclear winter” fears during the Cold War and the threat of nuclear ASAT use making large swaths of low-earth-orbital space uninhabitable for unhardened satellites due to the excitation of the Van Allen radiation belts that could persist for months or years. The latter effect would be far less cataclysmic, and more easily generated, than the former, but both would have global and relatively long-term consequences that bear heavily on the deterrence calculus for prospective attacks that might trigger such results.
Differences: An Abundance of Uniqueness
These and other parallels between nuclear and space deterrence, and between nuclear and space power more generally, are significant and can be illuminating; failing to be aware of them would certainly be unfortunate. On the other hand, not recognizing the differences between the two subjects can be actively perilous, leading to misconceptions that invite strategic surprise and major policy missteps.
Theory
In spite of the similarities identified above, nuclear deterrence and space deterrence aren’t really parallel concepts. Indeed, it is not entirely clear that space deterrence is a very useful construct – we do not speak of air or naval deterrence as distinct categories, after all, because of the degree to which conventional warfare in different do-mains is usually intermingled. Military space activities, too, are intimately connected to operations and capabilities in the other domains. This is not to say that deterring attacks against satellites and other space-related targets is not a matter of importance, only that it is a policy problem that may be less separate from other deterrence challenges than is often assumed.
Yet space really is different – the unique operating environment and, above all, the physics of orbital mechanics, create an operational and strategic world in which conventional wisdom often does not apply. The same can be said of nuclear strategy and deterrence, but it does not follow that because space and nuclear power each work differently from conventional military power they must then resemble each other. For example, during the Cold War it was often noted that nuclear weapons could turn familiar notions of offense and defense upside down: Strategically, threatening to attack an enemy’s nuclear arsenal was offensive, but threatening to annihilate enemy cities was fundamentally defensive, albeit unsavory. Similarly strategic defenses threatened to undermine deterrence if they protected a superpower’s cities, but not if they only defended its retaliatory nuclear capabilities. In space warfare, too, the meanings of offense and defense familiar from settings such as air warfare become inverted, though in a different way. In this realm, attacking enemy satellites even over one’s own territory is reckoned to be offensive counter-space activity, while protecting one’s own satellites as they overfly the enemy is defensive.
More central to space deterrence, it is worth considering a very basic question: Is attacking another state’s satellites a step up the escalation ladder from attacking terrestrial forces, or a step down?(20) Discussions about how to deter antisatellite attacks often take for granted the idea that, if possible, we should try to contain the use of force within the atmosphere, frequently proposing that the US government declare redlines to emphasize that ASAT attacks will be treated as extremely grave offenses, inviting severe responses. One could look alternatively at warfare in space and conclude that with a low expected body count, it should be considered milder than terrestrial conflict. Chinese writings that touch on this subject generally adopt a perspective that sees attacks on enemy space systems as unexceptional. The point here is not that one attitude is the correct one, but that the answer is sufficiently ambiguous that there is considerable potential for deterrence to be complicated by a lack of common thinking between the parties concerned. Such misunderstandings are by no means impossible when it comes to nuclear deterrence, but they are more likely to be limited in scope given the power of nuclear threats to concentrate the mind.
Destructiveness
The most fundamental difference between nuclear and space weapons and, in turn, between nuclear and space deterrence, is one of the simplest: Nuclear weapons are extremely destructive. This can seem like a truism, certainly everyone knows that it is true, yet it is surprisingly easy to discount – perhaps the clearest illustration is the frequency with which we refer to “weapons of mass destruction” or even “CBRNE” weapons – lumping nuclear weapons together with vastly less destructive ones.(21)
The reason we speak of “the absolute weapon” and “the nuclear revolution” is that the difference in destructive power between conventional and nuclear explosives makes the latter qualitatively different from the former, with relatively modest arsenals being capable of inflicting truly catastrophic harm on an enemy in relatively short order. (22)
Crucially, in many cases, even a state that is losing a war would be able to threaten to inflict such harm against a successful adversary. It is this result of the coupling of nuclear weapons with airpower and missiles that makes nuclear strategy and nuclear deterrence distinctive. Among states with reasonably robust nuclear arsenals, all that is really required is a reasonable expectation that one’s retaliatory capabilities will not be eliminated or disabled by an enemy’s first strike. There are very powerful incentives to avoid war, or to avoid very much escalation if a limited conflict does break out. This does not mean that deterrence will never fail or that escalation will always be controlled, but the deck should be relatively well stacked in favor of strategic stability and successful deterrence.
For space weapons and space deterrence the situation is very different. There may still be strong reasons for mutual restraint, but the prospect of catastrophic human costs if a war breaks out in space or if a terrestrial conflict spreads there is not likely to be one of them. Instead, one of the reasons that attacks on space systems might be attractive is their potential to cause the enemy great military or economic harm without generating a large body count. Indeed, some early advocates of space weapons development argued for the merits of shifting military competition and conflict into space at least partly on such humanitarian grounds. (Even nuclear weapons might be employed in space without killing many people, possibly none at all.) (23)
Consequently, there is little reason for leaders to quail at the prospect of using weapons in space during a conflict as they do with respect to employing nuclear weapons. To be sure, attacking an enemy in space would likely appear to be a dramatic action of much import, particularly because it would be largely unprecedented. However, once the decision to go to war, or even to risk war, against a powerful enemy has been taken, the significance of also employing space weapons is likely to be figuratively, as well as literally, marginal. The problem of convincing an enemy that is willing to fight the United States within the confines of the atmosphere that it should not also be willing to extend that conflict to space, if doing so appears militarily advantageous, is a daunting deterrent challenge.
Another consequence of the destructive power of nuclear weapons is that once a state possesses even a fairly small number of deliverable nuclear weapons, the size and sophistication of its arsenal is likely to matter less for deterrence than the apparent willingness to use it. Under most circumstances, credibility is less of an issue for anti-satellite weapons – threats to employ them are more likely to be believed because the intrinsic costs of doing so will be lower – but their actual capabilities will tend to be in doubt until they are demonstrated. Therefore, the incentives to offer such demonstrations prior to a conflict may be great, either for deterrent or compellent leverage.
Strategic Stability
We have already mentioned the issue of stability and first-strike advantage in nuclear and space strategy when discussing nuclear-space parallels, noting that both nuclear and space weapons tend to be hard to defend against. However, this similarity at the tactical and operational level breaks down on a broader scale. Viewed strategically, nuclear weapons tend strongly to favor the defense because it is so difficult to disarm a competent nuclear-armed opponent decisively through aggressive action, given that even a small number of surviving weapons can matter so much. In space, on the other hand, offense dominance scales up: a power that strikes aggressively should be, in theory, able to get the upper hand, or at least get the greatest possible use out of what-ever offensive counter-space capabilities it has invested in.
One of the reasons for this difference is that space weapons, and military space capabilities more generally, derive their significance from the roles that they play and the impact that they have in terrestrial warfare.(24) One might still wage a space war in isolation, with no accompanying hostilities occurring on the planet below, but even in such a case losses of space capabilities, even the control of space itself, would matter because of how advantages gained in space subsequently might be translated into military, coercive or other benefits in the terrestrial arena. Nuclear weapons also can be closely coupled to terrestrial warfare but, at the end of the day, they tend to trump conventional uses of force.
Once again we need to recognize that offense or defense dominance is ultimately shaped by the weapons that states build and the doctrines they embrace. It is possible, by accident or design, to develop force postures that enhance or weaken stability even when the basic attributes of key military technologies lean in another direction – this is not a simple matter of technological determinism. That being said, however, the tendency for nuclear weapons to make conquest and aggression more difficult rather than easier is extremely powerful, although one reason that nuclear deterrence tends to be robust is that nuclear deterrence failures have such potential to be horrific, which is the fundamental mechanism underpinning mutual assured destruction. Space warfare has no analogue for such secure second strike capability that could be similarly stabilizing, in spite of potential options to threaten a spacefaring state with very great harm by attacking its highly valued space assets.
Conclusion
As this essay has sought to sketch out, the parallels between nuclear and space deterrence are thought provoking and potentially illuminating. However, each of these do-mains involves key characteristics that are unique to it, so understanding one does not imply or constitute mastery of the other. The sense that there ought to be a close coupling between the two subjects may be due in part to the fact that each is exceptional. Bernard Brodie bestowed the label “the absolute weapon” on nuclear arms, establishing a tradition that was carried on by generations of nuclear scholars.(25) These are profoundly unconventional weapons because of their immense and unrivaled destructive power, which fundamentally shapes deterrence involving them in many ways even though the basic principles of deterrence still apply.
Space has its own superlative: It is “the ultimate high ground.”(26) But this is a metaphor that must be handled with care. Space is not merely a higher-altitude version of air, it is a different operational environment, governed by a different set of physical laws. Orbital mechanics instead of aerodynamics make LEO space territorially indivisible; lack of traditional terrain or terrestrial weather create a unique landscape where it is difficult to hide; and time and distance operate on different scales than on the ground or in the air. This makes space ideal for performing some military functions, almost all of them involving the collection or transmission of information, and very ill-suited for others that can usually be far better performed by terrestrial or aerial systems that are not hundreds or thousands of miles away from their targets.(27) All of these considerations contribute to making space deterrence something different from nuclear or some other form of deterrence transplanted to a domain that is colder, darker and less familiar.
Because of the increasing centrality of nuclear, space and cyber issues to national security concerns in the 21st century, each of these deterrence domains (which we might respectively tag as “stronger, higher, faster” to borrow and reshuffle a familiar slogan) stands to be more and more important to deterrence problems in coming years. Each involves distinctive dynamics and accordingly needs to be addressed on its own terms. But in doing so, it is essential not to treat any of them in isolation from the others or from the broader field of deterrence, lest their interconnections, both in theory and in practice, be overlooked.
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(1) This essay reflects the views of the author, not those of any of his employers or the United States government.
(2) See Karl P. Mueller, “Strategic Airpower and Nuclear Strategy: New Theory for a Not-Quite-So-New Apocalypse,” in The Paths of Heaven: The Evolution of AirpowerTheory, ed. Phillip S. Meilinger (Maxwell AFB, Ala.: Air University Press, 1997), 279-320.
(3) As explained by Thomas Schelling in Arms and Influence (New Haven, Conn.: Yale University Press, 1966), coercion comprises deterrence and compellence, which resemble each other in most respects but differ in the nature of the coercive demand, with deterrence seeking to prevent a change of behavior and compellence seeking to cause one.
(4) Ibid.; Glenn H. Snyder, Deterrence and Defense (Princeton, N.J.: Princeton University Press, 1961). Coercion can also be distinguished from persuasion, which seeks to alter the target’s preferences or desires rather than merely to alter its calculations about how best to serve its existing interests.
(5) Forrest E. Morgan et al., Dangerous Thresholds: Managing Escalation in the 21stCentury (Santa Monica, Calif.: RAND Corp., 2008), 7-46.
(6) Referring to this as “positive deterrence” (Thomas W. Milburn, “What Constitutes Effective Deterrence?” Journal of Conflict Resolution 3, no. 2 (1959): 138-145) unfortunately never has caught on, but whether one accepts the use of the “deterrence” label for the category, such positive sanctions of reward and reassurance, or the lack of them, are central to explaining many a deterrence success or failure. For a relatively rare examination of the differences between using threats and promises, see David A. Baldwin, “The Power of Positive Sanctions,” World Politics 24, no. 1 (October 1971): 19-38.
(7) For more discussion of the whole subject in a small package, see Karl P. Mueller, “The Essence of Coercive Air Power: A Primer for Military Strategists,” Royal Air ForceAir Power Review, 4, no. 3 (Autumn 2001): 45-56, http://www.airpowerstudies.co.uk/site-buildercontent/sitebuilderfiles/aprvol4no3.pdf.
(8) For a more extensive discussion of the subject, see in addition to other essays in this volume Forrest E. Morgan, Deterrence and First-Strike Stability in Space (Santa Monica, Calif.: RAND Corp., 2010).
(9) See Martin C. Libicki, Cyberdeterrence and Cyberwar (Santa Monica, Calif.: RAND Corp., 2009).
(10) Karl P. Mueller, “Totem and Taboo: Depolarizing the Space Weaponization Debate,” Astro politics 1, no. 1 (Summer 2003): 4-28.
(11) This picture might look significantly different when considering the possibility of ASAT attacks using nuclear weapons. This would open the door to the use of one or a few weapons having disproportionately widespread effects, and the technological demands of adapting nuclear weapons and long-range ballistic missiles to the anti-satellite role are relatively small once one possesses and operates the systems for other purposes. However, it is worth keeping in mind that the incentives not to use nuclear weapons are quite powerful, even under fairly extreme circumstances. This does not mean that deterrence would necessarily succeed, but merely that the theoretical potential for nuclear ASAT use is likely to be quite a bit greater than the reality.
(12) During the height of the US-Soviet military confrontation, the interconnections between nuclear weapons and national security space capabilities were so intense that it was not uncommon to see the latter almost entirely through the lens of the former, as in David E. Lupton, On Space Warfare: A Space Power Doctrine (Maxwell AFB, Ala.: Air University Press, June 1988).
(13) See, for example, Barry D. Watts, The Military Use of Space: A DiagnosticAssessment (Washington: Center for Strategic and Budgetary Assessments, 2001).
(14) The onetime popularization of knowledge about and interest in nuclear weapons policy was by no means just an inevitable result of nuclear tensions and arms races. Rather, it owed much to deliberate efforts to broaden debates on the subject beyond the ranks of governmental and technical specialists. See, for example, Ground Zero [Roger C. Molander], Nuclear War: What’s in it for You? (New York: Pocket Books, 1982).
(15) As noted above, there are also other means of interfering with space activities that pose smaller resource demands, including jamming, cybertattacks and old-fashioned kinetic attacks against ground elements of space systems.
(16) The preeminent examination of motives for nuclear proliferation is Scott D. Sagan, “Why Do States Build Nuclear Weapons? Three Models in Search of a Bomb,”International Security 21, no. 3 (Winter 1996/97): 54-86.
(17) This is not to suggest that crises always precede wars, or that even when they do, they always present an opportunity for deterrence to succeed in the breach. Sometimes states simply decide that the deterrence calculus favors going to war and don’t bother with an 11th-hour showdown, or wish to avoid tipping their hand in order to execute a surprise attack.
(18) It is easy to forget that because space is very large, many types of ASAT attacks (or hypothetical space-to-earth attacks) would not happen instantaneously, due to interceptor flight times or the limitations of orbital mechanics. However, unambiguous warning of imminent attacks might be very late in coming, and in some cases recognizing attacks even after the fact could be problematic.
(19) Irving L. Janis and Leon Mann, Decision Making (New York: Free Press, 1977); Robert Jervis, Richard Ned Lebow and Janice Gross Stein, eds., Psychology andDeterrence (Baltimore: Johns Hopkins University Press, 1985).
(20) I have argued elsewhere (Morgan et al., Dangerous Thresholds ) that the antediluvian metaphor of a ladder of escalation is best avoided for a host of reasons, not least being that one cannot accidentally fall up a ladder. But for the moment we will carry on with Herman Kahn’s questionable term.
(21) CBRNE stand for chemical, biological, radiological, nuclear and high-yield explosive. On the other hand, it is true that the “nuclear weapons” category is itself a broad one, comprising both fission and thermonuclear weapons that differ in explosive power by several orders of magnitude – not altogether different in degree from the divide between modern conventional munitions and atomic bombs.
(22) The sheer magnitude of the damage expected from a nuclear war was foreshadowed by interwar expectation about the horrors that might be expected from a second world war. See, for example, Uri Bialer, In the Shadow of the Bomber (London: Royal Historical Society, 1980) and George H. Quester, Deterrence Before Hiroshima(New York: Transaction Publishers, 1986).
(23) People concerned about anticipating potential threats to US security in space some-times raise the specter of al Qaida or some other extremist group gaining possession of a nuclear-armed ballistic missile and firing it into space in order to damage American satellites. Setting aside the aspects of such a scenario that make it far-fetched, were terrorists actually to acquire such a weapon and insist on using it, it is hard to think of a more benign place to have them detonate a nuclear warhead.
(24)Robert Preston et al., Space Weapons, Earth Wars (Santa Monica, Calif.: RAND Corp., 2002).
(25) Bernard Brodie, ed., The Absolute Weapon: Atomic Power and World Order (San Diego: Harcourt, 1946); Bernard Brodie, Strategy in the Missile Age (Princeton, N.J.: Princeton University Press, 1959).
(26) For example, Benjamin S. Lambeth, Mastering the Ultimate High Ground: NextSteps in the Military Uses of Space (Santa Monica, Calif.: RAND Corp., 2003).
(27) Often implicit in the “ultimate high ground” metaphor is an assumption that higher is better, but of course this is not true of traditional high ground. High mountain peaks are too far removed from things of military importance, and are too inaccessible, to be of much practical military interest – as the Siachen Glacier vividly illustrates. Similarly, for most purposes, military aircraft are not optimized to operate at very high altitudes.
Karl P Mueller is a senior political scientist at the RAND Corporation and a professor at the Pardee RAND Graduate School. He specializes in research related to military and national security strategy, particularly coercion and deterrence.
Editor's note:
This article was originally published by the Stimson Center on 27 September 2013 as part of an essay collection entitled "Anti-satellite Weapons, Deterrence and Sino-American Space Relations".
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