by George Rathjens

In consideration of whether the United States should go ahead with the deployment of some kind of missile defense system, it may be useful to raise questions of three kinds: (1) technical performance of defenses, particularly of national missile defense (NMD), against hypothesized threats; (2) the development, acquisition, deployment and possible use of weapons by other countries which might be engendered by an NMD deployment; and (3) the broader, longer-term effects on world politics and international relations of an American defense decision and the responses to it of other countries.

In respect of all three kinds of questions, but most particularly the first two, it is important to draw a very sharp distinction—much sharper than is sometimes done—between the requirements for defense (particularly of population and civil infrastructure targets) against nuclear weapons on the one hand, and against conventionally-armed weapons on the other.

Whether a defense is worth buying will, in principle, depend on (1) the importance or value of the targets that might be attacked; (2) the probability of successful interception of warheads that might strike them; and (3) the cost of achieving that probability of interception compared to the cost of the offensive weapons. In general, with increasing probability of interception, the cost of defense will rise much faster than linearly. For effectiveness in the range of, say, ten percent, the cost of defense may be less than that of the offense. Unless the damage that can be inflicted by offensive warheads that leak through such defenses is substantial compared to the cost of attack, there is, therefore, the possibility that the defense may "win" the offense-defense game (as happened famously in the Battle of Britain in World War II). Though the dismal performance of Patriot defenses against SCUD missiles in the Gulf War might suggest otherwise, this could happen again in the future, whatever kinds of offensive delivery vehicles are involved, provided their warheads are conventional (or chemical). Thus, some kinds of defense, such as theater missile defenses (TMD) against missiles so-armed, might be militarily sensible.

But against an attack by nuclear (or, perhaps, biologically)-armed missiles, it is a different ball game; and it is this kind of attack that has stimulated interest in a nationwide defense of the United States. Nuclear weapons are so destructive, and industrial societies so fragile (a single warhead might well cause many billions of dollars in property damage and the loss of many hundreds of thousands of lives), that even a ninety percent-effective defense may have only limited appeal. Because defense costs increase so dramatically as demanded effectiveness approaches one hundred per cent, it is generally unrealistic to think in terms of NMD costs of less than many tens of billions, or perhaps one hundred billion, dollars. Less costly—and less effective—defenses might be nice to have and perhaps worth buying if the only threats of concern were of accidentally- launched missiles, but they would hardly be of much interest against deliberate nuclear attacks, even by rogue states (or to use the now more politically correct descriptor, "states-of-concern"). If this is the principal issue, an important question is whether a nuclear attack by a "state of concern" against the United States would more likely be deterred if the US had an NMD, but no defense against delivery of weapons of mass destruction by other means, than if it had no defense at all. Or, to ask a probably more germane question: ‘would the US, if it had a hundred billion dollar NMD, be more likely take actions that it might be deterred from taking had it no NMD?’

The bottom line is that, in specifying performance criteria for judging whether the US should build an NMD, it is important that there be a clear understanding about the purposes for the defense. Currently we have no such understanding, since many NMD supporters just favor defense, never mind the details or the explication of purpose. With little understanding of the likelihood or probable cost of realizing an effective defense as a function of the objectives to be met and counter-measure possibilities, such supporters seem willing to go along with almost any rationale. The position is not quite as absurd as when Ronald Reagan talked of a defense that ‘would make nuclear weapons impotent and obsolete’, but it is distressing that from much discussion, both in the US and Europe, one gets the impression that the NMD question is more a matter of political will than of technical feasibility.

But even if one assumes the possibility of an NMD deployment that might be cost-effective in a narrow sense against hypothesized near-term "threats", it would seem fair to question the wisdom of proceeding with such a defense if it seemed plausible that doing so might induce putative adversaries—and/or others—to take actions that would imply a reversal in cost-benefit conclusions. Proponents of a US NMD deployment have often been explicitly dismissive of such hypothesized reactions, or have seemingly not even considered the possibilities. Confronting the likelihood (or probability) of such reactions has, however, been a staple in discussions of national missile defense by most opponents. For example, it has been suggested that in reaction to a US NMD, deployed ostensibly only to cope with "rogue state" missiles, China might accelerate its missile development and acquisition efforts, and that Russia might withdraw from arms control agreements and increase the numbers of MIRVed warheads on its missiles. And it has been suggested that a US NMD deployment would have divisive effects in NATO and pose "difficult problems" for some governments, that of the UK being most commonly cited.

Any or all of these things might happen, but would this necessarily be bad for the United States—and/or for other parties? How bad and why bad? Would it really make war more likely or the world less stable if START III were not consummated because of a US NMD deployment decision; or if Russia were to re-MIRV some of its missiles; or if China doubled its investment in ballistic missiles? Would such responses really lead to any government making different decisions in crises? Seemingly, most of those arguing against NMD, some perhaps overly-conditioned by old ‘Cold-War’ thinking, simply take it for granted, that ‘yes, such effects of NMD deployment would be bad, maybe even catastrophic’.

Commentary to the effect that collapse of the ABM Treaty regime would be an especially dire (and virtually inevitable) consequence of a US commitment to NMD is particularly illustrative of entrapment in this old thinking.

Arguably, an ABM treaty made great sense for both the United States and the Soviet Union during the thirty or so worst years of the Cold War, when it was widely accepted in both countries, at least at governmental levels, that severe mutual limitations on ABM defense could be key to dampening a wasteful offensive-defensive strategic arms race. This was because it seemed likely then that any deployment of defenses by either side could be, and almost certainly would be, offset—and, considering the propensity of military planners for "worst case analysis", perhaps more than offset— by an increase in offensive capabilities. But these con ditions no longer obtain. While there still may be something in the "action-reaction" theory of the arms race, Russia is in no position to engage in such a race with the United States now, nor is any other country. Thus, perpetuation of the ABM Treaty would limit American freedom of action but not, in any meaningful way, that of Russia or any other state. Small wonder, then, that Russia—and China—vigorously oppose termination or erosion of the ABM Treaty, the more so as the world may appear, at least to them, to be drifting more and more towards polarization, and American policy towards unilateralism.

All but the last few lines of this discussion suggest—or are at least are meant to suggest—that not much of a case can be made for or against the US going ahead with an NMD if one considers only its likely cost, effectiveness and the probable immediate political and military responses of other states. Such a defense might save some lives in the event of nuclear-armed missiles being launched accidentally, but it is unlikely to be effective enough to make a significant difference in America’s capability to protect itself or its other interests against other threats, or in its freedom of action to intervene in international crises.

But the reference above about a polarizing international order does hint at what may well be significant long-term negative consequences of a US NMD deployment.

With the fall of the Berlin Wall and the demise of the Soviet Union, many people looked forward to a new world based much less on confrontation between states, and more on cooperation and on a greater acceptance of common values and the rule of law than had characterized most of the post-World War II decades. Even George H. W. Bush spoke of a "new world order" at the time of the Gulf War. Since then, though, things have taken a turn for the worse, particularly in Russo-American and Sino-American relations.

The reasons for this retrogression are complex, but surely some critical decisions by each of the parties, coupled with "worst case" analysis and projections, have been major factors. First place among unwise decisions for which the US must bear major responsibility must surely go to NATO enlargement, but implementation of a US NMD deployment plan could prove to be a close second. This is not because such deployment would make a "first strike" by the US against Russia or China more likely, in the belief that such a defense could cope with Russian or Chinese missiles that might survive such an attack. Nor would it be because NMD would change the "military balance" in the world in any other meaningful way. Rather, it would be because influential people everywhere, but most notably in Russia and China, would interpret the US going ahead with an NMD as a reflection of gross American insensitivity to the concerns and interests of others and as a portent of an increasingly confrontational international order.

Such reactions are likely to be meaningful in adversely affecting the future actions of the great powers. They will be less likely to be able to resolve disputes that involve them directly in a peaceful fashion, and more likely to act precipitately and unwisely in crises, with possibly catastrophic consequences. They will also be less able to collaborate constructively in crises involving third parties. And the likelihood is that such reactions among the great powers would be exploited in their domestic politics to whip up support for leaders who would be relatively unconcerned about perpetuation and exacerbation of international differences.

Thus, a US decision to proceed with an NMD should be viewed not so much as an economically wasteful and otherwise unwise military decision, but rather as a monumental political blunder that will exacerbate mistrust and tensions, particularly among the great powers, the probable result being an increase in the frequency and long term seriousness of crises that could lead us where nobody wants or intends to go.

George Rathjens has been Pugwash Secretary General since 1997. For the preceding twenty-nine years he was a professor of political science at MIT. He has also held positions in the US Departments of Defense and State, in the US Arms Control and Disarmament Agency, and in the office of the President’s science advisor.

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