Russian President Boris Yeltsin, U.S. President Bill Clinton, Ukrainian President Leonid Kuchma, and British Prime Minister John Major signing the nuclear Non-Proliferation Treaty, December 1994
Russian President Boris Yeltsin, U.S. President Bill Clinton, Ukrainian President Leonid Kuchma, and British Prime Minister John Major signing the nuclear Non-Proliferation Treaty, December 1994
Win McNamee / Reuters


The case for Ukrainian acquisition of nuclear weapons rests fundamentally on two key arguments: first, Ukrainian nuclear weapons will promote peace and stability in a region that might otherwise be prone to conflict; and second, nuclear weapons will enhance Ukrainian security, providing an ultimate security guarantee for a state fearful that its sovereignty might otherwise be jeopardized by its enormous and potentially menacing neighbor to the east—Russia.

These are not trivial or easily dismissable arguments. They suggest that Ukrainian acquisition of nuclear weapons would produce desirable and beneficial security consequences for both Ukraine and the West. At first glance, they appear to provide a convincing rationale for Ukrainian nuclear weapons.

Nevertheless, Ukraine should not become a nuclear power. Its own interests and those of the West will best be served if Kiev fulfills its oft-made pledges to join the Nonproliferation Treaty (NPT) as a nonnuclear weapon state. The benefits provided by nuclear weapons are less certain and more conditional than the proponents of nuclear proliferation believe. When the costs and complications associated with nuclear acquisition are taken into account, the case for Ukrainian nuclear weapons is not compelling.


The case for nuclear proliferation rests on the pacific effects of nuclear weapons. As Kenneth Waltz asserts in the most famous advocacy of proliferation, nuclear spread "will promote peace and reinforce international stability." Because nuclear weapons greatly increase the costs and risks of war, they induce caution in the behavior of states and substantially reduce the likelihood of miscalculation. Wars between nuclear-armed states become simply too dangerous to fight. The force of this argument is greatly strengthened by the experience of the Cold War, in which the two bitterly opposed protagonists avoided war for nearly half a century despite numerous crises and provocations.

If nuclear weapons reliably cause peace, then nuclear proliferation to Ukraine—or any other state, for that matter—is not merely acceptable, but desirable, stabilizing a situation that might otherwise be prone to conflict. But there are a number of reasons to question whether nuclear weapons will promote peace and stability in all conditions and circumstances and whether they will have the desired effects in the particular case of Ukraine.

The Cold War was in fact "the long peace"; for all the tensions and crises of the postwar era, war between the United States and the Soviet Union was avoided. It is widely believed that nuclear weapons contributed substantially to this outcome—a view that I share.

But accounts of the long peace invariably focus on a number of other explanations, including the stability created by the existence of a bipolar international order, and the rough equality of military power between the two protagonists in the Cold War. In the most extensive analysis of the long peace, John Lewis Gaddis identifies no fewer than seven factors contributing to the stability of the Cold War system. These include bipolarity; the remarkable independence of the United States and the Soviet Union from each other, economically and geographically; the existence of domestic structures on both sides that, whatever their other merits or faults, did not undermine international peace and stability; nuclear weapons; the exploitation by both sides of advanced reconnaissance technologies that reduced the risk and fear of surprise attack; the ideological moderation of the Cold War protagonists in preferring international order to ideological purity; and the evolution of an implicit set of rules for the superpower game.

It is difficult to assess the impact of nuclear weapons when other powerful factors were also working to stabilize the U.S.-Soviet rivalry. Nuclear weapons may have been a major, or even the dominant, contributor to superpower peace during the Cold War. But given the existence of other powerful causes, it is also plausible that nuclear weapons have not been a significant factor in determining the course of the postwar era. Hence, the proposition that nuclear weapons promote peace and stability is properly regarded not as a fact but as an interpretation, largely based on the evidence of a single case.

Explanations of the long peace indicate that insofar as nuclear weapons have caused peace, they have done so in the context of a distinctive set of conditions. Virtually none of the conditions noted above now exist in relation to Ukrainian nuclear weapons. A Russian-Ukrainian nuclear relationship will not exist within a bipolar international system. Ukraine will be unable, over the long run, to maintain a rough equivalence in military power with Russia, which has three times the population and many times the geographical expanse and exploitable resources of Ukraine. Far from being geographically distant and highly independent, Ukraine and Russia are neighboring states with borders still described by some in Moscow as merely "administrative"; and they are deeply interdependent, economically and culturally. Because both Kiev and Moscow are in the throes of internal transformation, it is uncertain whether their future domestic structures will be conducive to peace, nor is it clear that ideological moderation will prevail in both capitals. Many years may pass before Ukraine will possess—if ever—the independent reconnaissance capabilities necessary to provide reassurance against surprise attack. And while rules of the game for Russian-Ukrainian relations may eventually evolve, they do not now exist.

Thus, most of the factors working for peace in Soviet-American relations are absent from the Russian-Ukrainian context. Nuclear weapons may have contributed to peace during the Cold War, but that is no guarantee that they will have the same effect in dramatically different settings and conditions.


Advocates of nuclear proliferation argue, however, that the logic of the nuclear-peace paradigm is so powerful that it applies across the wide range of domestic, regional and international conditions. Nuclear weapons are so clearly and unquestionably destructive that even a small risk they might be used is enough to stay the hand of decision-makers contemplating war. Nuclear weapons make it easy for states to ensure their security. Hence, in this logic nuclear-armed states "should" be confident of their security, prudent in their international behavior, insensitive to the military posture and policies of their adversaries, avoid arms races and spend less on defense.

This logic is impeccable. Unfortunately the behavior of nuclear-armed states has failed to conform to these predictions. The United States and the Soviet Union, for example, seemed to feel remarkably insecure during the Cold War, given their size, power and nuclear status. Apart from avoiding war with one another, their behavior was not invariably prudent, as evidenced by a series of dangerous confrontations. Far from being insensitive to the military preparations of the other side, both countries were obsessed by them. By the standards of modern history, they spent unusually large shares of their national treasure on defense. And throughout the Cold War the United States and Soviet Union opted for precisely the war-fighting nuclear doctrines that are regarded as unnecessary, inappropriate and destabilizing by most deterrence theorists.

If nuclear deterrence theorists ran the world, the benign and beneficial effects of nuclear weapons might be assured. The actual perceptions and behavior of policymakers in nuclear-armed states are much less reassuring.


It is rarely argued that nuclear weapons will magically solve the problem of conflict in its entirety. While all-out or high-stakes wars may become too dangerous to fight, there is still room for lesser challenges at lower levels of conflict. If the nuclear balance is believed to be highly stable, then decision-makers may calculate that they can fight even substantial conventional wars with little risk of escalation, since all parties possess enormous incentives not to use nuclear weapons. In addition, nuclear deterrent threats will not be equally effective in all circumstances; deterrence will not work well when dealing with ambiguous borders or disputed territories—a point that may be highly relevant to Russian-Ukrainian relations.

But conventional conflict in a nuclear environment raises the risk not only of intentional nuclear escalation, which leaders will have incentives to avoid, but also of inadvertent nuclear escalation, which leaders may not be able to avoid even if they want. A conventional war could jeopardize nuclear deterrent capabilities directly or degrade other important capabilities, such as warning systems, thus increasing the possibility of successful nuclear preemption. The most extensive analysis of this question concludes that the problem of inadvertent escalation will "loom especially large for small and medium-sized nuclear powers, since they will have the most difficult time building nuclear forces that can survive." This point clearly applies to Ukraine.

There are a number of considerations specific to the Ukrainian case that undermine the argument that nuclear weapons will enhance Ukrainian security and lead to international stability. Many of these concerns have to do with the risks and dangers associated with the transition to nuclear status.

The perils of expropriating nuclear weapons. Ukraine possesses an unusual path to nuclear status: it can take control of the Soviet strategic nuclear weapons deployed on its territory. However, Ukraine's ownership of these weapons is contested by Russia; the weapons are formally under the control of the Commonwealth of Independent States and are de facto in the operational control of Russia. There is no indication that Russia will willingly hand over these weapons to Ukraine. This raises the possibility of confrontation, crisis or, in the worst case, conflict between Russia and Ukraine, should Kiev move to take custody of these weapons.

The risks of "instant" proliferation. If Ukraine does succeed in obtaining custody of some or all of the nuclear weapons on its territory, it will have become, in effect, an "instant" nuclear power. Unlike other nuclear states, it will not have experienced a protracted, multiyear nuclear development program during which appropriate organizations and procedures can be created, personnel can be trained and thinking can be adjusted. While Ukraine has undoubtedly inherited some military personnel who have expertise derived from their involvement in the Soviet nuclear program, its government will inevitably be inexperienced in nuclear weapons matters and in the immediate future will lack a coherent nuclear establishment.

Even those who argue the benefits of nuclear proliferation are attentive to the risks of such a situation. Waltz, for example, frames his entire analysis in terms of the slow spread of nuclear weapons, suggesting that the long lead times normally associated with nuclear acquisition lessen some of the potential dangers of nuclear proliferation, and offering the conclusion that "rapid change may be destabilizing." The slow spread of nuclear weapons gives states time to learn how to live with them, to appreciate their virtues and to understand the limits they place on behavior.

Custodial dangers. Ukraine will not have immediately in place a mature framework for providing safe and secure custody of the nuclear weapons in its possession. This is a critical gap because organizational and procedural safeguards are necessary if nuclear safety and security are to be assured; technical safeguards alone (insofar as they exist) do not suffice. Hence, the standard worry that nuclear proliferation will increase the risk of inadvertent or unauthorized use, or the risk of nuclear terrorism, may initially be all the more acute in the case of Ukraine. Instability in Ukraine only exacerbates this concern.

Nuclear instability between Russia and Ukraine. There are also serious questions about the stability of the nuclear relationship between Russia and Ukraine, in both the short and the long run. The near-term situation would be quite precarious. If Ukraine succeeds in becoming a nuclear power by taking custody of the nuclear weapons on its territory, the locations, capabilities and vulnerabilities of those weapons will be known in intimate detail by Russia; initially, Moscow will probably know more about these weapons than Kiev. Ukraine presently lacks any warning capability whatsoever. And it would likely take some time before Ukraine had an operational nuclear capability. Thus, Ukraine would pass through an initial period of substantial nuclear vulnerability—potentially raising a preventive war temptation for Moscow.

The situation is not easy to remedy over the longer run. Ukraine will face a number of difficult constraints in attempting to construct a survivable deterrent force. The proximity of Russia and Ukraine means that Kiev is condemned to live with short warning time, even when it possesses early warning capabilities. Survivability measures based on exploitation of warning—such as alert and evacuation programs for aircraft and many schemes for mobile missiles—will be unavailable to Ukraine. While not landlocked, Ukraine has access only to the Black Sea, which does not provide a viable sea-based option. Fixed land-based sites are considered vulnerable, given the accuracy and lethality of modern nuclear systems. As the American experience has shown, developing survivable command and control for nuclear forces is neither cheap nor easy; it will not be surprising if Ukraine experiences grave concerns about the threat of nuclear decapitation. Moreover, Ukraine may be, in the manner of the two Germanies, particularly vulnerable to espionage, given that Russia and Ukraine share both the Russian language and Slavic backgrounds, while millions of people with Russian ancestry reside within Ukraine's borders. Accordingly, Russia may have access to unusually good intelligence about Ukraine's nuclear capabilities, even over the long haul.

These factors provide a recipe for endemic instability. Even the United States, with its many thousands of warheads and multiple means of delivery, was recurrently plagued with vulnerability crises throughout the Cold War. Ukrainian leaders will, for good reason, be considerably less confident in the survivability of their nuclear deterrent forces—a situation that would probably lead to first-use doctrines and hair-trigger postures. While there is no doubt that any attack on nuclear forces would be risky, this scenario leaves plenty of room for clever briefers and for dangerous "use them or lose them" pressures.

Political instability in Ukraine. Ukraine is in the midst of a dramatic political transformation. Its politics are unsettled, its economy is struggling, its society is ethnically divided and democracy is not deeply rooted. The internal uncertainties in Ukraine amplify many of the dangers described above. What if Ukraine comes to be led by authorities who do not harbor "appropriate" thoughts about the character of nuclear weapons? What if internal unrest disrupts nuclear custodial arrangements? What if nuclear weapons get caught up in civil strife? The potential for trouble is obvious.


Ukraine's leaders will be rightly concerned first and foremost with Ukrainian security. The fundamental question for them is not whether nuclear weapons will produce international stability, but whether, on balance, they will improve Ukraine's capacity to defend itself. As an independent and sovereign state, Ukraine has every right to make the preparations it thinks necessary for its security. Having just emerged from several centuries of subjugation to Moscow, Ukrainians will be intensely aware of the need to defend their sovereignty. Hence, if there is not a plausible case that Ukraine is better off without nuclear weapons than with them, then the international community's worries about the dangers of nuclear proliferation will probably be moot; Ukraine will look after its own interests. But there is a case to be made that the security benefits provided to Ukraine are outweighed by the costs of nuclear acquisition. At least eight considerations lead to this conclusion.

First, as mentioned previously, Ukraine cannot take custody of the nuclear weapons on its territory without running a considerable risk of military intervention by Russia. Even if this is avoided at first, Ukrainian seizure of these weapons will create powerful preventive and preemptive motivations in Moscow, increasing the risk of intervention in subsequent confrontations. Grabbing these weapons could provoke the very war Ukraine professes to fear.

Second, taking control of the nuclear weapons on its territory guarantees that Ukraine will be regarded as a necessary target by all nuclear states who fear that they could conceivably be threatened by Ukrainian forces—including the United States, since most of the nuclear systems in Ukraine were designed for intercontinental missions against U.S. territory. Forgoing nuclear weapons cannot protect Ukraine against nuclear risks, although some limited protection may be offered by the international norm that nuclear threats should not be made against nonnuclear states and by the taboo against nuclear use. But nuclear acquisition is one of the few things Ukraine could do that would both ensure and legitimize nuclear threats against it.

Third, Ukraine will inherit only incoherent fragments of a meaningful nuclear weapons capability. The missiles on its territory are more suitable for striking the United States than Russia, and must be modified to Ukraine's relevant security needs. Russia may possibly leave behind disabled, rather than functional, nuclear weapons; Moscow has little incentive to make things easy for Kiev. Nor will Ukraine initially possess the nuclear weapons production complex necessary for the restoration and maintenance of its nuclear arsenal. These considerations reinforce the point that in the short run Ukraine is likely to experience a dangerous period of extreme vulnerability.

Fourth, Ukraine will be condemned to nuclear inferiority, possibly over the long run. Russia possesses thousands of warheads and a vast nuclear production complex, and it will be able to invest more resources in maintaining and modernizing its nuclear forces. Ukraine's nuclear force will be much smaller. In the short run, it could be wholly vulnerable. Over the longer run, it could remain substantially vulnerable—a fact that will be a perennial source of worry and instability. This situation will limit Kiev's nuclear options and make any threat or use of nuclear weapons by Ukraine extremely dangerous for Ukraine.

This leads to a fifth, particularly important, point: Ukraine's nuclear force will be deterred by Russia's under most circumstances. The risks for Ukraine of initiating a nuclear exchange will be so great that its deterrent threats will lack credibility in all but the most extreme contingencies. Proponents of a Ukrainian nuclear force will argue that nuclear weapons will provide an ultimate guarantee of Ukraine's sovereignty, that its nuclear threats will be credible if faced with conquest. But it makes little sense to use nuclear weapons even in that situation. As even Waltz points out, "If their national existence should be threatened, weaker states ... may destroy themselves through resorting to nuclear weapons."› If a bold, reckless or highly motivated nuclear opponent should calculate similarly, Ukraine's ultimate deterrent may be unreliable. Russia, of course, would still have to confront the risk that Ukraine would carry out its nuclear threat, however irrational that might be, and this should provide some deterrent benefit. But Ukraine cannot gain that benefit without exposing itself to perilous risks.

Even if nuclear weapons provide some ultimate safeguard for Ukraine's sovereignty, they clearly do not solve all of its security problems. Not one nuclear weapon state has found its security rendered quiescent by the fact of its nuclear capabilities. For each, threats continued to exist and crises continued to happen. Most nuclear powers have found themselves in one or more conventional wars despite their nuclear capabilities. Each has maintained a considerable conventional capability; indeed, there is a high correlation between nuclear status and possession of some of the world's largest and most formidable conventional military establishments. And there is no evidence to suggest that nuclear-armed states are insensitive to the conventional preparations of their adversaries. The United States, after all, possessed more than 20,000 nuclear weapons but nevertheless still spent over 80 percent of its defense budget on conventional assets to counter the conventional forces of the Soviet Union and its allies.

Hence, a sixth consideration is all the more important: despite the myth that nuclear weapons are cheap, they are in fact quite expensive for most states. If Ukraine wished to become a medium nuclear power on the order of Britain or France, for example, it would have to spend at least $3 billion to $5 billion per year on its nuclear capabilities—and probably more, since British and French nuclear expenditures are reduced because of their nuclear cooperation with the United States. Five billion dollars constitutes the overwhelming fraction of the defense budgets of all but the six or seven largest defense spenders in the world. Given Ukraine's economic needs and constraints, there will surely be incentives to minimize the resources devoted to defense, and the sums associated with a medium nuclear capability will surely be painful for Kiev.

The economic burden for Ukraine will be substantial, but the trade-offs between conventional and nuclear forces will be even more difficult. In view of its economic problems, Ukraine will be unable to become a medium nuclear power without making significant sacrifices in its conventional capabilities. From the point of view of Ukraine's security, this trade-off is unfortunate. Conventional forces, unlike nuclear, are useful to confront a whole range of security challenges that Ukraine might face. The costs of nuclear weapons could so weaken Ukraine conventionally that it might be unable to defend itself conventionally in extreme contingencies. Kiev would thus have the options of suicide or surrender—hardly a desirable state of affairs.

Ukraine is, in terms of population, resources and geographic expanse, one of the largest states in Europe. Ukraine could generate considerable conventional combat power; even now it inherits a considerable conventional capability from the Red Army. While Kiev will never be able to match Moscow in a conventional arms race, it is capable of mounting a credible conventional deterrent. Decision-makers considering a conventional attack are highly sensitive to anticipated costs and are likely to be deterred if they cannot count on achieving a quick, cheap victory. By adopting a conventional deterrent strategy, Ukraine could muster enough conventional capability to make any major military action against it a costly exercise—but the financial costs of nuclear status could undermine such an approach.

Proponents of Ukrainian nuclear weapons like to pose Kiev's alternatives as nuclear weapons or insecurity. This is doubly wrong: Ukraine is neither wholly secure with nuclear weapons nor, taking into account the conventional deterrent option, completely insecure without them. Certainly there are risks associated with a conventional deterrent strategy, but this is no less true of a nuclear deterrent strategy.

A seventh consideration bears on Ukraine's security problems and military options: for Ukraine to exercise its nuclear option would have a damaging effect on the arms control frameworks that presently apply to Russian and Ukrainian forces and territory. The first and second Strategic Arms Reduction treaties would be most directly affected, since Russian ratification of the former and acceptance of the latter are conditional on Ukraine's accession to the NPT as a nonnuclear state. But the tension and acrimony that would surely accompany Ukraine's move to nuclear status could also undermine the Conventional Forces in Europe agreement, the Helsinki Confidence and Security Building Measures regime, and the Open Skies Agreement. Since these agreements together limit Russia's ability to deploy forces in the area west of the Urals, restrict and require notifications of major troop movements and exercises, and institutionalize high levels of transparency, they are very much in Ukraine's security interest. Indeed, they increase the viability of a conventional deterrent strategy. On the other hand, Ukraine's security predicament will be much worse if these agreements are undone.

Finally, Ukraine cannot exercise the nuclear option without damaging its relations with the United States and other Western states, all of whom are steadfastly opposed to nuclear proliferation. Although Western states, without exception, want good relations with Ukraine, most will make nuclear Ukraine pay a price, if only to discourage other potential proliferators. Further, at least in the United States, Congress is so strongly opposed to nuclear proliferation that the Clinton administration would probably be unable to avoid imposing sanctions even if it wanted.

For Ukraine, then, there will be a tension, if not a trade-off, between the nuclear option and its basic grand strategic impulse to integrate with the West. And the potential costs are considerable. Going nuclear will increase the risk of isolation. By breaking its many pledges to denuclearize, including those negotiated directly with Washington, Kiev will have proven its unreliability as a negotiating partner, a fact that will certainly diminish incentives to cut future deals with Ukraine. Moves to expel or suspend Ukraine from international institutions would not be surprising. Its prospects for aid from and trade with the West would be harmed, a setback that has security implications given the importance of economic strength to national power. And even Ukraine's military potential would be hurt, since some major arms suppliers, including the United States, have policies or laws against arms transfers that contribute to a proliferator's military posture.

To be sure, some of these costs would probably be transitory, not all of these measures would necessarily be taken, and not all states would certainly support sanctions. But there would be real, meaningful, unavoidable political, economic and military costs to Ukraine if it exercises the nuclear option.


The nuclear-peace paradigm has a seductive appeal. It implies a simple and powerful solution to the problem of war. It promises peace and stability where otherwise conflict and confrontation might reign. The small risk of nuclear use, it is claimed, will deter anyone from going to war.

In fact the opposite is true; even a small risk of war despite nuclear weapons makes nuclear proliferation too dangerous to contemplate. Nuclear war is by no means inevitable if Ukraine gets nuclear weapons, and under some circumstances nuclear weapons may promote peace and stability. But embracing the proposition that nuclear weapons cause peace should be leavened with an appreciation of the factors cutting in the opposing direction. Advocates of Ukrainian nuclear weapons are betting that the logic of the nuclear revolution will prevail over the potential dangers of nuclear proliferation. And they could be right. Yet there is also a chance that they will turn out to be wrong. As John Mearsheimer has written, "Mismanaged proliferation could produce disaster, while well-managed proliferation could produce an order nearly as stable as the current order. Unfortunately, however, any proliferation is likely to be mismanaged."fi When one considers the stakes and the risks involved, the gamble is too great to take.

Fortunately, Ukraine has already opted for the nonnuclear path. This choice enables Kiev to avoid the great costs and risks of nuclear acquisition and leaves it financially better able to develop its conventional capabilities. All things considered, there is no reason to persuade Ukraine to reverse the nonnuclear policy to which it has been explicitly committed since well before it attained independence.

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  • STEVEN E. MILLER is Director of Studies at the Center for Science and International Affairs at the John F. Kennedy School of Government, Harvard University.
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