A “Nuclear Umbrella” for Ukraine? Precedents and Possibilities for Postwar European Security

Whatever the outcome of Russia's war against Ukraine, in its wake Ukrainians will need to choose a security policy to defend their sovereignty from future threats. Their choice holds implications for broader European security. Some observers, and many Ukrainians, advocate Ukraine's membership in the North Atlantic Treaty Organization (NATO), under the assumption that the “nuclear umbrella” provided by the United States to its European allies will protect the country from attack.¹ Others are less confident in the effectiveness of what has been called extended nuclear deterrence—the threat of U.S. nuclear retaliation for attacks, including those carried out with conventional armed forces, on an ally's territory.² Would moving the Cold War's Iron Curtain to Ukraine's eastern border and reconstituting a version of NATO's old nuclear posture provide adequate security? Or should alternatives to nuclear deterrence—many of them studied and advocated during the Cold War itself—get a new hearing?

Nuclear deterrence is widely credited with having preserved the peace in Europe throughout the Cold War. This claim assumes that there was something to deter: an invasion by the armed forces of the Soviet Union into the NATO countries. The archival evidence that has emerged following the breakup of the Soviet bloc reveals no such intention on the Soviet side. What Robert Jervis wrote more than twenty years ago remains true today: “The Soviet archives have yet to reveal any serious plans for unprovoked aggression against Western Europe, not to mention a first strike against the United States.”³ Moreover, crises that raised the specter of nuclear use—most notably over West Berlin before the building of the Berlin Wall in 1961—suggest both the danger and the dubious credibility of extended nuclear deterrence.

Unlike the Soviet leaders, Russian President Vladimir Putin has demonstrated a willingness to launch a major war in Europe. By invoking the legacy of imperial Russia and rejecting the borders of the independent states that emerged from the breakup of the Soviet Union, Putin has laid claim to vulnerable territory of NATO members—naming specifically the Russian-populated Estonian city of Narva, on the Russian border. If Ukraine and the rest of Europe face a Russian leadership far more aggressive and less cautious than its Soviet predecessors, they may not want to stake their security on the assumed nonuse of nuclear weapons. The history of the end of the Cold War offers a number of alternative possibilities for pursuing security through a mix of nonoffensive conventional military means and nonviolent civilian resistance. They are worth updating for Europe's present and future.

The current conventional wisdom on European security counts on expanding NATO and expecting its members to pay more for security in the face of evident Russian aggression.⁴ This approach implicitly or explicitly relies on extended nuclear deterrence. Other proposals for Ukraine's future defense fall short of NATO membership but include a commitment to continuing the vast military support that NATO, particularly the United States, has been supplying to Ukraine since the Russian invasion of 2022.⁵ But NATO may fail to provide the capability that Ukraine needs for its defense.

The problem with the conventional wisdom is that it does not adequately address the future of Ukrainian or European security. It is a policy of more of the same: more money and more members without resolving the security dilemma in which Russia and NATO are locked. If the Russo-Ukrainian War ends with some kind of territorial compromise, as most observers expect, both sides will undoubtedly be dissatisfied with the settlement. Politically, Crimea and the Donbas could play the role of Alsace-Lorraine, claimed by both France and Germany after the Franco-Prussian War, and a contributing factor in the subsequent world wars. A stable security arrangement would need to provide confidence to both Russia and Ukraine that the other side would not try to overturn the peace settlement by force.

Extended nuclear deterrence is not up to the task. It remains a costly and risky approach to Russian aggression. It stakes too much on the hope that Putin (or his successors) would refrain from actions that could provoke nuclear retaliation—even after he has ignited the biggest armed conflict in Europe since World War II and continues to menace NATO members with the threat of nuclear attack. There are, fortunately, other ways to defend Ukraine in the long term and restore European security. One promising option would be to adopt a non-offensive strategy of territorial defense—what has become known as “confidence-building defense,” in combination with civilian-based nonviolent resistance, to deter future aggression. This approach would alleviate the security dilemma that some claim contributed to Russia's 2022 invasion and provide a more stable post-conflict environment. Others may find it odd to invoke the concept of the security dilemma and seek to reassure a country that has already engaged in massive military aggression.⁶ But a long-term, reliable peace for Ukraine and Europe will require addressing the legitimate security concerns of both Ukraine and (ideally) a post-Putin Russia. Threatening nuclear retaliation is not the way to do it.

To set the table for discussions of a future security arrangement, particularly in Europe, it is important to first clear the table of questionable arguments about how nuclear weapons have affected European security. I present and challenge claims about the effectiveness of nuclear deterrence, lay out theoretical concepts that informed discussions of European security during the Cold War and remain useful today, and offer a brief historical summary of the relationship between nuclear weapons and Soviet military strategy in Europe. I then review the role of nuclear deterrence during the Berlin crisis of 1961. Preserving access to West Berlin posed the greatest challenge to NATO's security policy. The attempt to address it through extended nuclear deterrence illustrates the catastrophic risks entailed—risks that reliance on nuclear weapons still poses in cases such as Narva.

The goal of this article is to present alternatives to nuclear deterrence that emerged during and at the end of the Cold War and to apply them to Ukraine today. European peace researchers and their U.S. counterparts promoted notions of “common security” and non-offensive or nonprovocative defense as ways to reduce reliance on nuclear weapons.⁷ Their ideas contributed to the peaceful end of the Cold War and the East-West military confrontation in Europe. Yet, with the disintegration of the Soviet Union, the alternative defense strategies were never fully implemented. NATO countries considered them unnecessary, and post-Soviet Russia viewed them as a hindrance to its military operations against Chechnya and its neighbors in the “near abroad.”

My main argument is that the alternative approaches of the late Cold War can provide the basis for a stable defense for postwar Europe and Ukraine. The goal is to provide for Ukrainian security in a Europe menaced by Russian expansion, without relying on the threat of nuclear war. I examine counterarguments based on conventional deterrence by denial through NATO and continued military support for Ukraine, and demonstrate why a non-offensive, non-nuclear approach is a safer choice.

In July 2017, meeting at United Nations’ headquarters in New York, 122 countries voted in favor of a legally binding treaty to ban nuclear weapons. The Treaty on the Prohibition of Nuclear Weapons (hereafter, the Nuclear Ban Treaty) entered into force in January 2021, after the first fifty signatories had ratified it.⁸ The nuclear powers refused to join, and the nuclear-armed members of NATO went one step further: In a joint press statement, the United States, the United Kingdom, and France vowed never “to sign, ratify or ever become party to” the Nuclear Ban Treaty.⁹ What reasons did they offer to oppose the majority of the world's countries that considered their security better served by abolishing nuclear weapons than by possessing them? “This initiative clearly disregards the realities of the international security environment,” they declared. “Accession to the ban treaty is incompatible with the policy of nuclear deterrence, which has been essential to keeping the peace in Europe and North Asia for over 70 years.”¹⁰ In November 2020, NATO Secretary General Jens Stoltenberg claimed that the alliance's “ultimate goal is a world free of nuclear weapons,” but he insisted that “in an uncertain world, these weapons continue to play a vital role in preserving peace” and the NATO countries would be the last to give them up.¹¹

NATO leaders’ confidence in nuclear deterrence stemmed from their understanding that nuclear weapons had preserved the peace throughout the Cold War by preventing “conventional” war between the major powers. Popular movements for nuclear disarmament had considered the policy too risky and sought alternatives. In the second half of the 1980s, such “nuclear abolitionists” were joined by reformist Soviet leader Mikhail Gorbachev and U.S. President Ronald Reagan, who shared the goal of eliminating nuclear weapons, although most of Reagan's advisers, and many NATO leaders, disagreed with their stance.¹² British Prime Minister Margaret Thatcher, for example, insisted that Gorbachev's efforts to achieve nuclear abolition were misguided. Meeting him in Moscow in March 1987, she asserted that “we do not believe that it is possible to ensure peace for any considerable amount of time without nuclear weapons. Nuclear weapons are the most powerful and most terrible guarantee of peace that was invented in the 20th century. There is no other guarantee.”¹³

Nearly three decades later, sounding much like Thatcher, Putin claimed that “nuclear weapons constitute a factor of deterrence and a factor guaranteeing peace and security throughout the whole world.”¹⁴ In the wake of the Russian invasion of Ukraine, it seems evident that the mere existence of nuclear weapons was insufficient to prevent the most destructive war in Europe since World War II. Russia's possession of nuclear weapons may even have emboldened Putin to launch the invasion, confident that deterrence would prevent direct U.S. intervention. “In the context of the Ukraine war,” writes Nina Tannenwald, “nuclear weapons have mostly benefited Russia.”¹⁵

The opponents of nuclear abolition would be the first to acknowledge that preventing a war in Ukraine was not what they had in mind in promoting nuclear deterrence. Nevertheless, one consequence of the war might be that advocates of nuclear weapons scale back their claims and ambitions. Are nuclear weapons still “essential to keeping the peace in Europe and North Asia,” or are they inadequate to the task?¹⁶ Do they continue “to play a vital role in preserving peace,” or do so only under circumscribed and uncertain conditions?¹⁷ Perhaps peace can be preserved, and wars prevented, only for some states, those sheltered under the U.S. nuclear umbrella (i.e., members of the NATO alliance, and maybe South Korea and Japan). Nicholas Rostow, a former legal adviser to the U.S. National Security Council, focused on precisely this concern in suggesting what was at stake in Russia's war against Ukraine: “Do we want a world in which the possession of nuclear weapons grants a license to commit aggression? Do we want a world where only formal allies of the United States may feel safe from aggression (if in fact they may)?”¹⁸

The claim that nuclear weapons preserved the peace was never true in places like Vietnam and Afghanistan, where the United States and Soviet Union fought devastating wars, or in other countries where they intervened militarily. It is worth questioning whether the claim is tenable for Europe, once it emerges from the Russian war against Ukraine. Evidence from the Cold War suggests that the conventional wisdom about the role of nuclear deterrence in Europe merits skepticism.

There are four theoretical concepts developed during the Cold War that help shed light on the history of nuclear deterrence in Europe and its utility today. Jervis's concept of the “security dilemma” is a good place to start. Second is his distinction between the “spiral model” and the “deterrence model.”¹⁹ The security dilemma applies to countries interested in maintaining the status quo. It asks whether they can provide for their own security without threatening the security of others. If two status quo powers pursue security at the expense of each other, they represent the spiral model and engage in competitive arms races that pose the risk of war. If one or more states is interested in expansion rather than the status quo, we observe the deterrence model: the status quo state seeks to deter the expansionist state, or two expansionist states try to deter each other.

A third useful concept is the “stability-instability paradox.”²⁰ Applied to the Cold War, it suggests that a stable relationship of nuclear deterrence, with the United States and Soviet Union each able to destroy the other in retaliation for a nuclear strike, produces instability at lower levels of conflict, with each side willing to take risks (such as during crises), confident that its adversary's fear of escalation would avoid nuclear war. One of the behaviors they might undertake is called “salami slicing” or “salami tactics,” whereby a state would make a certain encroachment calculated to be minor enough not to trigger an escalatory response, and then continue with other such encroachments until it achieved its expansionist aims.²¹ By definition, a state engaging in such behavior would not be considered satisfied with the status quo, and would be difficult to deter. Rather than risk nuclear escalation, the state facing such an aggressor could make its conquest untenable and too costly by pursuing a combination of direct defense of the threatened territory and mass civilian resistance.

Finally, there is Carol Cohn's insight about “technostrategic language.”²² She explains that sometimes the very terminology adopted by nuclear strategists obscures the question of state intentions altogether. If one side's weapons are vulnerable in a technical sense to a preemptive strike, the strategists assume that the other side would want to attack, regardless of the political or human context. By the same token, if the two sides each instead maintain a “secure second-strike capability,” and stability holds at the strategic level, then they would be tempted to make encroachments or engage in salami tactics at lower levels—again without regard to the political stakes.²³

During the Cold War, many U.S. strategists assumed that the United States was a status quo power, but they disagreed on how to characterize the Soviet Union. Sometimes they assumed that Soviet leaders would engage in military conquest if they were not deterred.²⁴ Other times they recognized spiral dynamics in Soviet behavior and sought to reassure Soviet leaders through efforts like proposing arms control measures that could bring stability to the relationship.²⁵

Much of our understanding of European security during the Cold War is founded on the assumption of Soviet aggressive intentions. In this reading, U.S. nuclear weapons deterred Soviet expansion. But some of the most dangerous crises of the early Cold War—the communist coup in Prague in March 1948 or the Berlin blockade three months later—took place under conditions of U.S. nuclear monopoly. Even at the outbreak of the Korean War in June 1950, the Soviet Union had tested only one atomic bomb, did not test more until 1951, and did not develop a reliable capability to retaliate with nuclear weapons against the United States until the 1960s.²⁶ The U.S. nuclear monopoly failed to intimidate Joseph Stalin, but fortunately, as is now understood, neither the Soviet dictator nor his successors harbored intentions to advance militarily against the European democracies.²⁷

After the defeat of Nazi Germany, war plans called for a strictly defensive reaction to the outbreak of another war—one that Soviet leaders assumed would begin with an invasion from the West. Until the plans were declassified as part of Gorbachev's policy of glasnost in the late 1980s, most observers, even if they assumed Soviet status quo intentions, expected that the Soviet Union, if attacked, would seek to avoid another war fought on its territory by immediately going on the offensive.²⁸ On the contrary, well into the 1950s, as Stalin began rebuilding the armies of the satellite states under Soviet occupation, their strategies “remained unequivocally defensive.”²⁹

Subsequent Soviet strategy—including the shift to an offensive orientation for the ground forces—exhibits elements of the spiral model. U.S. and European concerns about Soviet political and military expansion led to the formation of NATO in 1949 and the deployment of U.S. nuclear weapons on European soil. The rearmament and entry of the Federal Republic of (West) Germany into NATO in 1955 provoked the formation of the Warsaw Treaty Organization, or Warsaw Pact. Vojtech Mastny, one of the foremost authorities on the Soviet bloc military archives, attributes the shift toward a more offensive Soviet posture to the introduction of U.S. tactical nuclear weapons into Europe in the early 1950s. The Soviet plan—if NATO launched an invasion—was to try to seize or destroy the nuclear arms before they could be used. As the Soviet side nuclearized its own forces, its strategy depended on preemptive nuclear strikes if NATO were to attack.³⁰

The Soviet Union never launched an armed attack against NATO. Instead, the Soviet Army invaded fellow alliance members—Hungary in 1956 and Czechoslovakia in 1968—and directed menacing military exercises against Poland in the wake of the Solidarity (Solidarnonb) trade union movement in the early 1980s.³¹ NATO's nuclear weapons were not designed to deter this sort of Soviet military behavior. Western aid for the victims of Soviet aggression was limited to mainly rhetorical support. A system of “spheres of influence” emerged that produced a certain stability and seemed to mitigate the security dilemma (although at the expense of human rights).

The anomalous situation of Berlin constituted an exception to this generally stable situation. It posed the hardest challenge to extended nuclear deterrence and demonstrated the risks that such a strategy entails. Because those risks are relevant to a future European security arrangement in which NATO is expected to defend countries along Russia's border, the next section examines the case of Berlin in detail.

The product of a four-power occupation (France, Great Britain, the Soviet Union, and the United States) following World War II, Berlin remained divided between the Soviet sector in the east and a union of the French, British, and U.S. sectors in the west, politically affiliated with the Federal Republic of Germany (FRG), or West Germany. The German Democratic Republic (GDR), the communist-ruled Soviet ally known as East Germany, claimed Berlin as its capital. The city was located deep within East German territory, with several hundred thousand troops of the Soviet armed forces deployed nearby. With Soviet support, the GDR could easily deny access to the Western powers.

For the Western allies—France, Great Britain, and the United States—defending West Berlin from Soviet encroachment constituted their most difficult military challenge. They feared that the Soviet Union would engage in salami tactics, with West Berlin as the first slice. For the Soviet side, the city's anomalous situation was a constant uneasy reminder of the absence of a peace treaty to signal the end of World War II and to recognize postwar borders. Failing to agree on the conditions for a unified postwar Germany, the Western allies had established the FRG from their occupation zones in May 1949, and the Soviets created the GDR in October. In redrawing the postwar borders, in the wake of Red Army victories, Stalin had appropriated parts of eastern Poland to add to Soviet Ukraine. He compensated the Poles by giving them formerly German territories in east Prussia (including the port city of Danzig, now Gdaósk), after brutally expelling the Germans living there. Irredentism among the estimated twelve million refugees who settled in West Germany, and NATO's unwillingness to recognize the legitimacy of the East German communist regime, heightened Soviet fears that NATO would support military efforts to retake the territory. Particularly troubling was that West German Chancellor Konrad Adenauer insisted on the return of former German lands from Poland and Czechoslovakia.³²

Nikita Khrushchev, Stalin's main successor, wanted to avoid the spiral dynamics that would lead his military command to nuclearize the Soviet forces in reaction to NATO's tactical nuclear weapons. According to Mastny, Khrushchev hesitated to embrace the offensive preemptive strategy, hoping instead to reduce the chance of war by settling the Berlin question, recognizing the postwar borders, and normalizing East Germany's status. He harbored no intention of seizing or annexing West Berlin. Instead, Khrushchev had hoped to negotiate with U.S. President Dwight Eisenhower, or his successor, John F. Kennedy, an arrangement that would, as Vladislav Zubok explained, allow the “United States to acquiesce to the existence of ‘two Germanys’ just as they had acquiesced in, indeed supported the existence of, ‘two Chinas’ in the Far East.”³³ West Berlin would be accorded the status of a “free city.”³⁴ With the failure of the Vienna summit with President Kennedy in June 1961, however, Khrushchev vowed to put into effect his backup plan: a separate peace treaty between the Soviet Union and the GDR that would give the latter formal control over its territory, including access routes to West Berlin.³⁵ The risk of miscalculation, if the Western powers forcibly asserted their right to access the city in the face of East German opposition, “made the six months that followed the most dangerous period of the Cold War in Europe,” according to Mastny.³⁶

In September 1961, the Warsaw Pact defense ministers gathered for the first time to discuss military preparedness. The following month the Warsaw Pact forces undertook a major military exercise. The maneuvers, called Buria or Storm,³⁷ “impressed Western observers as being mainly for show,” writes Mastny.³⁸ The archival documents reveal, however, that they “actually served as a dry run for what the Soviet high command was preparing to do in case the conclusion of the treaty with East Germany provoked a military conflagration”³⁹ if, for example, the East German regime asserted its sovereignty over West Berlin, and the allies responded with armed force.

Buria imagined a signing of the treaty in early October 1961, followed by a closing of the lines of communication from western Germany to Berlin. According to the scenario, the NATO troops would seek to advance with ground and air forces toward Berlin. Blocked by Warsaw Pact forces, they would launch an all-out war with nuclear strikes. Because the Soviet forces would be primed to preempt NATO nuclear use in the European theater, the plan was ambiguous regarding who would actually strike first. Yet the estimate of the number of nuclear weapons exploded was more precise: some 1,200 on the NATO side and more than a thousand on the Soviet side—enough to render Europe uninhabitable.⁴⁰

For Mastny, the 1961 Berlin crisis was more serious than the Cuban missile crisis a year later. “Even after Khrushchev had abandoned the separate peace treaty project,” he writes, and after the construction of the Berlin Wall resolved the problem of mass exodus of East Germans, “the planning for a European war by his generals continued unabated.”⁴¹ Although Soviet strategy still assumed that NATO would initiate the war, the costly and risky plans of his generals threatened Khrushchev's goal to divert resources from military preparations to the civilian economy. In Mastny's view, “the adoption by Moscow of an offensive European strategy proved a lasting legacy of the Berlin crisis for a quarter of a century until the strategy was discarded under Gorbachev,” who also sought demilitarization for its economic benefits.⁴²

Looking at the crisis from the vantage of U.S. declassified documents reinforces the sense that Berlin posed a difficult dilemma for the Western powers and that their proposed solution—extended nuclear deterrence—courted disaster. In 1961, NATO developed a plan called LIVE OAK to respond to feared Soviet encroachment on West Berlin. The relevant documents, originally classified as “Cosmic Top Secret [sic]” were declassified and posted on a NATO website in 2011, with a brief introductory essay available in English, French, Russian, and Ukrainian.⁴³ The plan, outlined in a document dated September 27, 1961, signed by NATO Secretary General Dirk Stikker, called for up to a division of NATO's troops and three fighter squadrons to confront Soviet forces if air and ground access to the city were cut off—precisely what Khrushchev thought his East German allies might do. NATO intended a series of selected and graduated escalatory moves to arrive “at a settlement of the problem of Berlin while progressively making the Soviets aware of the danger of general war.”⁴⁴ General war in those days was a euphemism for nuclear war. The document declared explicitly that “the Alliance will stand ready for nuclear action at all times.” It specified the conditions under which NATO would use its nuclear weapons: “(1) prior use by the enemy, (2) the necessity to avoid defeat of major military operations, or (3) a specific political decision to employ nuclear weapons selectively in order to demonstrate the will and ability of the Alliance to use them.”⁴⁵

At the time, NATO's plans for extended nuclear deterrence held that the United States could threaten a retaliatory strike for action short of a nuclear attack on its own territory—a Soviet threat to West Berlin, for example—and thereby prevent it. Such a policy, combined with risky deployments of tactical nuclear weapons interspersed with conventional forces and strategic nuclear weapons on hair-trigger alert, always posed the prospect of catastrophic consequences. Research by Mastny and others show that the Soviet side was prepared to use nuclear weapons preemptively in the scenario war-gamed during Buria.

The NATO secretary general's report of September 27, 1961, mentioned the option “to employ nuclear weapons selectively” to demonstrate the alliance's will.⁴⁶ Back in Washington, however, plans for more immediate escalatory action were under review. President Kennedy had received a report the previous week with a proposal to launch a disarming counterforce first strike (i.e., a nuclear attack) to decimate Soviet nuclear capability if West Berlin came under attack. Recent satellite intelligence had indicated that despite Khrushchev's boasts of Soviet missile superiority, the Soviet Union possessed only four operational intercontinental ballistic missile (ICBM) complexes (along with many long-range bombers and shorter-range missiles armed with nuclear warheads).⁴⁷ Under those conditions, the report “concluded that a counterforce first-strike was indeed very feasible, that we could pull it off with high confidence,” although surviving Soviet nuclear weapons could still kill millions of people in the United States in retaliation.⁴⁸

Paul Nitze, then Assistant Secretary of Defense for International Security Affairs, criticized the proposal for a selective nuclear attack and advocated instead for the disarming first strike. He described how “at our meeting with the President, I suggested that since demonstrative or tactical use of nuclear weapons would greatly increase the temptation to the Soviets to initiate a strategic strike, it would be best for us, in moving toward the use of nuclear weapons, to consider most seriously the option of an initial strategic strike of our own.”⁴⁹ A U.S. first strike, Nitze claimed, “could assure us victory in at least a military sense in a series of nuclear exchanges, while we might well lose if we allowed the Soviets to strike first.”⁵⁰

Other Kennedy advisers, such as Theodore Sorensen and Marcus Raskin, were horrified by the first-strike proposal and that such a study had even been undertaken.⁵¹ Even though the technostrategic logic of which Cohn wrote points to its feasibility (achieving Nitze's “victory in a military sense”), Kennedy rejected the plan for a disarming U.S. first strike. But NATO's preferred alternative—a gradual escalation of U.S. nuclear attacks intended to coerce the Soviet side to back down—could also result in a nuclear holocaust. This was the approach advocated by renowned nuclear strategist Thomas Schelling and conveyed to President Kennedy: to engage in “deliberate, discriminating, selective use” of nuclear weapons to signal resolve to the Soviet side as part of a bargaining process and to treat the U.S. garrison as a kind of “tripwire” to convince the Soviet leaders that they were risking nuclear catastrophe.⁵² If the Soviet Union chose not to adhere to the arcane scenarios of controlled response devised by Schelling and other strategists, however, the situation could easily spiral out of control. Thus, Mastny's conclusion: “The Western theory and practice of deterrence, with its pointless nuclear posturing divorced from political realities, appears in retrospect as irrelevant in preventing a major war—which the enemy did not intend to start in the first place—as well as ineffective in preventing lesser abuses of military power,” such as restrictions on Western access to Berlin.⁵³

In sum, a plausible paraphrase of the NATO plan for defense of West Berlin, had it been conveyed to the Soviet leaders as a deterrent threat, might have been: “If you seize the city, we will blow up the world.” And the Soviet threat might have been: “If you try to enter Berlin by force, we will blow up the world.” Given how little each side understood of its rival's plans, this situation was potentially disastrous. No wonder prominent U.S. officials, as well as their European counterparts, harbored doubts about the credibility or plausibility of NATO's reliance on nuclear weapons. Henry Kissinger, national security advisor to President Richard Nixon in early 1969, for example, averred that extended nuclear deterrence “depended on a first strike” by the United States, something he claimed the European allies did not understand. Nixon concurred. The “nuclear umbrella in NATO” was, according to the president, “a lot of crap.”⁵⁴

The extreme version of the security dilemma, centered around the precarious situation of Berlin, was only resolved in the 1970s. A series of agreements associated with West German Chancellor Willy Brandt recognized two German states “in one nation,” and the 1975 signing of the Helsinki Accords confirmed the inviolability of Europe's existing borders and the territorial integrity of its states—relieving a major source of Soviet insecurity.⁵⁵

Whether such a political solution would be possible for European security after the war in Ukraine depends on the objectives of the relevant countries. In the 1970s, all sides were willing essentially to codify the status quo in a divided Europe. Yet, even once the apparent political sources of the European security dilemma had been alleviated, East-West relations still deteriorated in the late 1970s. Soviet intervention in Afghanistan contributed to the demise of détente, but the main issue in Europe was nuclear weapons, which at this point did less to preserve peace, as their advocates promised, than to exacerbate tensions. Tactical forces and intermediate-range nuclear forces had been excluded from the desultory Strategic Arms Limitation Talks (SALT). In December 1979, NATO responded to the Soviet Union's modernized intermediate-range nuclear forces (i.e., SS-20/RSD-10 Pioneer ballistic missiles) by deploying the nuclear-armed Pershing II ballistic and Gryphon ground-launched cruise missiles in four European countries. Popular opposition exploded in what became known as the Euromissile crisis.⁵⁶ Throughout the early 1980s, hundreds of thousands of protesters affiliated with the European Nuclear Disarmament (END) movement gathered in the main cities of Europe, while in the United States the Nuclear Weapons Freeze Campaign gained momentum.⁵⁷

In parallel with the protests, European scholars associated with peace research institutes began investigating alternatives to nuclear deterrence as a means to European security. Meanwhile, some U.S. scholars and activists became concerned about a variant of the stability-instability paradox—that the nuclear deterrent standoff between the so-called superpowers enabled the United States and the Soviet Union to intervene militarily in their respective spheres of influence. Some critics dubbed this phenomenon the “deadly connection” between nuclear weapons and conventional warfare.⁵⁸ The proposals that European and U.S. researchers promoted to reduce reliance on nuclear weapons arguably helped contribute to the end of the Cold War.⁵⁹ They are worth reviewing for the lessons they might hold for European security in the wake of the war in Ukraine.

That nuclear weapons could prevent war, or at least war among the major military powers, became an unassailable claim during the Cold War. Whether a period that entailed much suffering among victims of major power wars against smaller states and destructive civil wars throughout the world deserves the moniker the “long peace” is dubious.⁶⁰ But the belief in the power of nuclear weapons to deter war was strong enough that proponents of nuclear disarmament had to take it into account. European peace research scholars and U.S. activists found common cause in recognizing that the fear of conventional war served to justify the possession of nuclear weapons. Less sanguine about nuclear deterrence than representatives of the foreign policy establishment, peace researchers argued that providing a means to reduce the risk of conventional war could undermine the case for nuclear weapons.⁶¹ If alternative means of deterring or preventing war were available, nuclear weapons would appear unnecessary—and unnecessarily risky.⁶² After all, most states avoid war most of the time without possessing nuclear weapons. Certainly the members of NATO and the Warsaw Pact could figure out how to do so.

Alternatives to the nuclear-armed standoff in Central Europe had already appeared in the 1950s.⁶³ The prospect of a remilitarized West Germany entering the nuclear-armed NATO alliance produced a flurry of proposals for a nuclear-free zone and disarmament in Central Europe, with plans advanced by such prominent figures as Anthony Eden and Adam Rapacki, the foreign ministers of Britain and Poland, respectively.⁶⁴ Some focused directly on the military strategy of the new Bundeswehr, West Germany's army.⁶⁵ Several of the proposals emphasized non-nuclear, defensively oriented, militia-based ground forces intended for territorial defense and unsuited for offensive operations. Sweden, Switzerland, and Yugoslavia constituted examples of such defense strategies.⁶⁶ The goal was to provide reliable, nonprovocative defensive forces that would neither depend on nuclear deterrence nor present suitable targets for nuclear attack.⁶⁷ These forces would help reduce the tendency toward a security dilemma or spiral.⁶⁸ The proposals’ political prospects were poor, however, because Eisenhower's “New Look” emphasized nuclear deterrence, and NATO planned to integrate the emerging West German Bundeswehr into its nuclear strategy.⁶⁹

Alternatives to the nuclear status quo reappeared with the emergence of peace research institutes in Germany and Scandinavia in the 1970s.⁷⁰ Researchers, including some retired military officers, began studying ways of reconfiguring conventional military forces to provide reliable defense without including offensively oriented configurations of weapons that would pose a risk of escalation to war during a crisis. The underlying premise echoed Jervis's spiral model, and the proposals conformed to his prescription for cooperation under the security dilemma: neither of the two military alliances in Europe sought aggressive war, so non-offensive strategies would provide reassurance and stability without provoking an arms race. The peculiar German expression strukturelle Nichtangriffsfähigkeit (structural inability to attack) became widely known in the political discussions about security in the 1980s.⁷¹ Because the European researchers developed their proposals explicitly to reduce reliance on nuclear weapons, they sought to create defensive strategies that would avoid large concentrations of forces and equipment, so as not to provide tempting targets to a nuclear-armed adversary.⁷²

In the wake of the Euromissile crisis of the early 1980s, peace researchers’ long-standing skepticism about nuclear deterrence spread to the broader society. Many European citizens—as well as politicians from the Social Democratic and the Green parties—favored a principled antinuclear position. Their views found expression, among other places, in Defence without the Bomb,⁷³ a study by the British Alternative Defence Commission, and Common Security,⁷⁴ the report of the Independent Commission on Disarmament and Security Issues, chaired by former Swedish prime minister Olaf Palme.⁷⁵

With the passing of Leonid Brezhnev's generation and the advent to power of a reformist coalition led by Gorbachev, the proposals of the peace researchers received a serious hearing. Gorbachev and the members of his brain trust felt considerable affinity for Social Democratic politicians such as Palme in Sweden and Egon Bahr in West Germany, two of the main promoters of “common security.” Endorsement of the notion made it possible for Soviet civilian and military reformers to promote non-offensive defense as a path to reducing nuclear weapons. The United States and NATO, increasingly orienting their own strategy for war in Europe in an offensive direction with initiatives such as Follow-On Forces Attack, resisted proposals for defensive restructuring.⁷⁶ They took Soviet interest in disarmament seriously only after Gorbachev announced a dramatic unilateral reduction and restructuring of Soviet conventional forces at the United Nations in December 1988.⁷⁷ He explained that the army would be reduced by 500,000 troops and that six tank divisions would be withdrawn from Eastern Europe and disbanded. Soviet troops stationed in Warsaw Pact countries would be reduced by 50,000. Reductions in equipment focused on forces intended for offensive use, as Gorbachev described: “assault landing formations and units,” “assault river-crossing forces, with their armaments and combat equipment” and 5,000 tanks. “All remaining Soviet divisions on the territory of our allies will be reorganized,” Gorbachev proclaimed. “They will be given a different structure from today's, which will become unambiguously defensive, after the removal of a large number of their tanks.”⁷⁸

The Soviet unilateral initiatives paved the way for agreements to reduce both conventional and nuclear forces, much as disarmament activists had advocated and as Gorbachev himself had envisioned early in his term as Soviet leader.⁷⁹ Another element of Gorbachev's UN speech revealed its significance mainly in retrospect: his commitment to “freedom of choice” for any country to determine its own political system, including the members of the Soviet bloc.⁸⁰ No longer would Soviet allies be required to adhere to monopoly rule by a communist party receiving its orders from Moscow. The unilateral military restructuring and reductions and the political proclamation were linked: In the past, ideological conformity was enforced by the menace and practice of Soviet military intervention against its allies. Now the political threat and the military capability would both be eliminated. For these reasons, Gorbachev's speech can be understood as a turning point signaling the end of the Cold War in Europe and the opportunity to replace the nuclear confrontation there with an alternative security system. At least in Europe, the deadly connection between nuclear deterrence and military intervention was broken.

The Soviet unilateral initiatives provided impetus to the negotiations on conventional and nuclear forces and resulted in the first treaties that actually reduced U.S. and Soviet nuclear arsenals, including the entire category of intermediate-range nuclear missiles. The Treaty on Conventional Forces in Europe (CFE) entailed extensive reductions in forces and equipment. At a summit meeting in Paris in November 1990, leaders of NATO and the Warsaw Pact signed the CFE Treaty, joined a session of the Conference on Security and Cooperation in Europe (CSCE) the next day, and issued the Charter of Paris for a New Europe—effectively a declaration of the end of the Cold War.⁸¹ In place of the deadly connection, a more hopeful one beckoned. As the peoples of Eastern Europe heeded Gorbachev's call to exercise their freedom of choice, they chose to reject communist rule, mainly through peaceful demonstrations, without fear of military intervention. The connection between demilitarization and democratization seemed to fulfill the program advocated by many peace researchers and the activists of the END movement and their East European counterparts, a continent-wide effort to support human rights and peace.⁸²

Besides those hopeful visionaries, few could have anticipated the peaceful fall of communist regimes and the demilitarization and reunification of Europe even a half dozen years before. Only the most pessimistic prognosticators could have foreseen the brutal Russian offensive against Ukraine that began in February 2022. The deliberate destruction of civilian property and life, the war crimes, rapes, kidnapping and deportation of children, the Nazi-style atrocities—all led by a nuclear saber–rattling former KGB agent—were inconceivable as the Cold War was ending. To evaluate the plausible options that remain for postwar Europe, the next section reviews the trajectory from the hopeful vision to the horrendous reality.

Some features of the settlement that ended the Cold War promised more than they delivered. Consider the CFE Treaty. Negotiated by the two Cold War alliances, it allocated restrictions on a bilateral basis, with overall limits on weapons and personnel, and regional ceilings within those limits. Its main achievement was the verified destruction of tens of thousands of tanks, armored combat vehicles, attack helicopters, aircraft, and the like. Typically, states destroyed their oldest equipment. In the early 1990s, an international team of scholars led by Randall Forsberg hoped to build on the momentum of the European conventional force reductions and theories of non-offensive defense to limit the production and export of offensive military aircraft that would be used for military intervention in favor of air defense systems.⁸³ Had the initiative succeeded, its impact on wars of the first quarter of the twenty-first century could have been considerable.

Contrary to the expectations of many peace and human rights activists and Russian officials, disarming and reducing conventional armed forces did not portend the dissolution of the bloc system in favor of a continent-wide security organization. The Organization for Security and Cooperation in Europe (OSCE) replaced the CSCE in November 1994, but it did not provide the means to maintain either security or cooperation. Nor did it supersede the alliance system, as many of its proponents had hoped. Instead, only the Warsaw Pact dissolved. NATO expanded, both geographically within Europe and militarily, with missions as far afield as Afghanistan, Libya, Somalia, and Yemen.

The combination of Warsaw Pact dissolution, NATO enlargement, and Russia's military ambitions in the former Soviet space caused problems for the CFE Treaty. The military structure of the Warsaw Pact was formally dismantled in April 1991. By the time the CFE Treaty went into effect in November 1992, only one of the alliance parties that negotiated it—NATO—still existed. The six former Warsaw Pact states that ratified the treaty—Bulgaria, Hungary, Poland, Romania, and the successor states to Czechoslovakia (the Czech Republic and Slovakia)—became members of NATO during enlargement rounds in 1999 and 2004. In the latter year, the three former Baltic republics of the Soviet Union—Estonia, Latvia, and Lithuania—also joined.

Even before the the Soviet Union dissolved, the country's military command had attempted to evade some of the CFE limitations. For example, it moved massive amounts of equipment to the east, beyond the treaty's geographic sweep from “the Atlantic to the Urals.” In the early 1990s, Russian President Boris Yeltsin pushed to revise the treaty to allow deployment of military forces beyond the regional limits, particularly in the North Caucasus military district.⁸⁴ The objective was apparently for military forces stationed there to pressure, and, eventually, to invade the breakaway republic of Chechnya without violating the treaty. Eager to gain Yeltsin's acquiescence to NATO expansion, the Bill Clinton administration approved a revision of the treaty and generally disregarded the Russian massacres of Chechen civilians.⁸⁵ The Adapted CFE (ACFE) Treaty, as it was called, was signed in 1999, but NATO members never ratified it. They insisted that Russia remove its troops from Moldova and Georgia, where the Russian military propped up the separatist regions of Transdniestria, Abkhazia, and South Ossetia. Russian military interventions in the “near abroad” were arguably inconsistent with the spirit of the treaty, if not the letter.⁸⁶ In retrospect, imposing such conditions might have been a mistake: had the ACFE Treaty been implemented, with its provisions for regular reporting and inspections, it could have hindered Russia's preparations for military intervention in Ukraine.⁸⁷

Russia, in turn, raised concerns about NATO's compliance with the treaty. It objected to the prospect of NATO troops deployed in the territories of new members (i.e., Bulgaria, Estonia, Latvia, Lithuania, and Romania). The three Baltic countries, still part of the USSR at the time, had not joined the original CFE Treaty, nor had they ratified the ACFE Treaty. They were therefore legally unconstrained in hosting NATO troops on their territories that bordered Russia. NATO would have been willing to include the Baltic states in the ACFE Treaty, but Russia insisted that the Baltic NATO members ratify it first and they refused. In 2007, Putin suspended Russia's participation in the treaty, a move that even Gorbachev supported.⁸⁸

In June 2008, Russia raised the possibility of negotiating a revised “security architecture” for Europe when the then president Dmitry Medvedev made a speech in Berlin calling for a “Euro-Atlantic security system that is equal for all states—without isolating anyone and without different levels of security.”⁸⁹ But even when the Russians submitted a draft treaty to that end, it remained thin on substance and seemed oriented primarily to sideline NATO and the OSCE and to contain further NATO expansion, following the alliance's overtures to Georgia and Ukraine. Commitments to human rights, freedom of choice of political system and security alliance, and reorientation of military forces toward defense—the hallmarks of the agreements that ended the Cold War—were noticeably absent.⁹⁰

If there remained any doubt, the Russo-Georgian war of August 2008 made clear that the notion of “non-offensive defense” that motivated many proponents of the CFE Treaty no longer held any interest for the Kremlin. Russian forces launched offensives to seize and occupy several Georgian cities, and Russian missiles and aircraft bombed the capital city of Tbilisi. Following its invasion, Russia recognized the independence of the secessionist regions of South Ossetia and Abkhazia, just six months after Kosovo had declared its independence from Serbia—the result of Serb repression of Kosovar Albanians and NATO's decision to respond with a seventy-eight-day bombing offensive in March 1999. Thus, Russia was not the only country intent on maintaining offensive capabilities.

In the nuclear domain, the promises of the Cold War's end remained unfulfilled. The implementation of the Intermediate-Range Nuclear Forces (INF) Treaty, negotiated under the Reagan administration, marked the high point of bilateral nuclear disarmament. Instead of pursuing an agreement with post-Soviet Russia, the administration of George H. W. Bush, Reagan's successor, unilaterally reduced U.S. tactical nuclear weapons, including sea-based ones.⁹¹ Its main accomplishments in the nuclear sphere entailed cuts in strategic forces in the Strategic Arms Reduction Treaties (START), and convincing Belarus, Kazakhstan, and Ukraine to return the Soviet nuclear weapons deployed there to Russia. Bolstered by a grassroots transnational antinuclear movement in Kazakhstan, Gorbachev's government had agreed to phase out the Semipalatinsk nuclear test range and push for a Comprehensive Nuclear Test Ban. The Russian successor government negotiated and signed it in 1996 and ratified it in 2000, after independent Kazakhstan had closed Semipalatinsk.⁹² In return for reluctant support from the U.S. nuclear weapons laboratories for the treaty, the Clinton administration paid off the labs with annual budgets for “stockpile stewardship” of more money than they had received when they were producing nuclear weapons at the height of the Cold War.⁹³ Although the United States signed the treaty, the U.S. Senate voted against ratification in 1999.

Not surprisingly, as the process of nuclear disarmament stalled in the 1990s and the political relationship between the United States and Russia deteriorated, both countries reverted to Cold War thinking about nuclear weapons—or worse. Against the spirit of the Antiballistic Missile Treaty of 1972, the United States pursued ballistic missile defenses (BMD) until the George W. Bush administration formally withdrew the United States from the treaty and announced plans to install BMD radars on the territories of new east European members of NATO. Barack Obama revised and expanded plans for European missile defense, and ultimately signed congressional legislation authorizing nearly $64 billion for BMD programs.⁹⁴ Each of these steps met with criticism from the Russian side and helped bring the cooperative “end of the Cold War” era to an end.⁹⁵

Russia's most significant contribution to derailing the process of nuclear disarmament came in the realm of strategy rather than military hardware. Under the Yeltsin administration, Russia officially abandoned the commitment of Soviet leaders not to be the first to use nuclear weapons. Faced with a conventional army in serious disarray—it had effectively lost the first round of the war in Chechnya in 1996—Russia seemed to be adopting NATO's Cold War approach of using nuclear deterrence to compensate for conventional weaknesses. Moreover, its purported strategy of “escalate to deescalate” suggested a new willingness to launch nuclear weapons preemptively.⁹⁶

Disarmament proponents had long hoped that the antinuclear efforts initiated by Gorbachev and Reagan would stigmatize nuclear weapons. The countries that signed the Nuclear Ban Treaty sought the same end.⁹⁷ The actions of the United States and Russia instead demonstrated that the two countries were unwilling to do what nearly every other country in the world tries to do: provide for security without threatening mass murder of other countries’ civilians. Their behavior over the last decades, and especially since Russia intervened in Ukraine in 2014, portends grave consequences for European security.

President Obama, who advocated a world without nuclear weapons in a speech in Prague in 2009,⁹⁸ left office after approving a nuclear “modernization” program estimated to cost $348 billion, including maintenance and infrastructure, by 2024.⁹⁹ The most recent estimate is that the United States will spend $756 billion over 2023–2032.¹⁰⁰ The budget includes funding to modify and upgrade the B61 nuclear bomb, intended for deployment with aircraft in five NATO countries. The weapon's yield reportedly varies from 0.3 to 10 kilotons. For comparison, the biggest “blockbuster” bombs of World War II were 6 tons, and the bomb that destroyed Hiroshima was about 15 kilotons.¹⁰¹ That the B61 is intended for both strategic and nonstrategic purposes seems an invitation to escalation, as an adversary would not know which version is employed and might assume the worst.¹⁰² With lower yields of the nuclear explosives, and the potential to limit radioactive fallout, the new weapons could be seen as more usable, thereby lowering the nuclear threshold and increasing the risk of escalation to all-out war.

The centerpiece of U.S.-Soviet initiatives for European nuclear disarmament ended in August 2019, when the United States withdrew from the INF Treaty and Russia followed suit. The treaty required the United States and the Soviet Union to eliminate 2,692 nuclear and conventional ground-launched ballistic and cruise missiles with ranges from 500 to 5,500 kilometers and to permit unprecedented on-site inspections. The Obama administration's State Department had accused Russia of violating the treaty by testing a ground-launched cruise missile with a range that exceeded the treaty's maximum. In February 2017, Donald Trump's administration accused Russia of secretly deploying an operational unit of the missile, known as Novator 9M729.¹⁰³ Two years later, the United States suspended its obligations and announced that it intended to withdraw if Russia did not come into compliance in six months. Putin denied the charges and vowed to match any new intermediate-range missile that the United States might deploy—a clear reversion to the tit-for-tat pattern of the Cold War nuclear arms race that Jervis had theorized as the spiral model and that Gorbachev's “new thinking” had rejected in favor of common security.¹⁰⁴

In addition to its alleged treaty violations, Russia raised the danger of nuclear war in many ways. It developed new hypersonic weapons, maintained an arsenal of tactical nuclear weapons unregulated by any treaty, deployed some of those weapons to Belarus, made explicit nuclear threats, and issued a statement about the circumstances under which it might use nuclear weapons—actions that go well beyond the Cold War policies of the Soviet Union.¹⁰⁵ According to the “Basic Principles of the Russian Federation's State Policy in the Domain of Nuclear Deterrence,” a document Putin signed in June 2020, Russia reserves the right to initiate use of nuclear weapons “in the case of aggression against the Russian Federation with the use of conventional weapons, when the very existence of the state is put under threat.”¹⁰⁶ In justifying Russia's invasion of Ukraine, Putin used precisely this language. He claimed in his speech on February 24, 2022, that U.S. actions in Ukraine—whose basic legitimacy as an independent state Putin disputed—constituted “not only a very real threat to our interests but to the very existence of our state and to its sovereignty.”¹⁰⁷ In other words, Putin already presented the casus belli for initiating nuclear war, when he chose to characterize Ukraine's actions and NATO support of the country's defense as “aggression.” Subsequently, in August 2023, the United States reportedly began preparing to deploy the B61-12 nuclear bomb to aircraft in England.¹⁰⁸

For many observers, the current risk of nuclear war is greater than during some of the darker days of the Cold War. Putin's explicit threats to use nuclear weapons (albeit in response to whatever he considers aggression against Russia) and the dangerous attacks in, around, and from Ukraine's civilian nuclear installations indicate a level of recklessness not seen since the Cuban missile crisis. They demonstrate a striking disregard for the dangers posed by a nuclear meltdown or explosion.

It is difficult to assess the risk-taking propensities of Putin. Some might argue that the decision to invade Ukraine indicates a high degree of recklessness, given how poorly the “special operation” went. Others might point to the faulty intelligence and exaggerated assessments of Russian military capability that led some to anticipate a relatively easy success (although flouting international law even with an “easy” invasion of a neighboring country manifests a certain degree of recklessness).¹⁰⁹ The risks inherent in the Russian behavior around the Zaporizhzhia nuclear power plant lend credence to the first interpretation—Putin as a reckless gambler. It gives rise to the concern about what he might do next. What if Putin, who seems preoccupied with his role in history (as the successor to Peter the Great in one speech),¹¹⁰ decided on a high-stakes gamble, a military initiative that could plunge the world into nuclear war if it failed, but could destroy the NATO alliance if it succeeded?

In his speech on June 9, 2022, Putin hinted at a suitable target: the Estonian city of Narva. Addressing a group of young scientists and engineers, as the war in Ukraine dragged on longer than he had presumably expected, Putin praised Peter the Great for waging “the Great Northern War for 21 years” and establishing the city of St. Petersburg—Putin's hometown—as a second capital to complement Moscow: “When he founded the new capital, none of the European countries recognised this territory as part of Russia; everyone recognised it as part of Sweden. However, from time immemorial, the Slavs lived there along with the Finno-Ugric peoples, and this territory was under Russia's control. The same is true of the western direction, Narva and his first campaigns. Why would he go there? He was returning and reinforcing, that is what he was doing.”¹¹¹ Here Putin echoes one of his long-standing themes and aspirations—the “in-gathering of Russian lands” (sobiranie Rusi)—whose practical consequences included the illegal annexation of Crimea and creation of pro-Russian protectorates in the Donbas, as well as repression of critics at home.¹¹²

When Putin launched his first military operations against Ukraine in 2014 and annexed Crimea, the people of Narva—closer geographically to St. Petersburg than to the Estonian capital of Tallinn—had good reason to worry that they might be next. In fact, some analysts had called attention to Narva's predicament earlier, in the wake of Russia's 2008 war with Georgia.¹¹³ Putin's justification for intervening in Ukraine, however, elevated these concerns because it seemed plausible that a similar justification could be applied to aggression against Estonia.¹¹⁴ Taking a page from the dictator who vowed to bring all German-speaking peoples together under one Reich, Putin had posed as the protector of Russian-speaking Ukrainians purportedly suffering genocidal discrimination by the Ukrainian government.¹¹⁵

In Narva more than 95 percent of the population are native speakers of Russian. Nearly 88 percent are ethnic Russians.¹¹⁶ If Putin claimed that the Estonian government were committing “cultural genocide” against fellow Russians, it would not be hard for him to create an incident to justify Russian military intervention on “humanitarian” grounds. The military effort itself would be far less taxing than seizing Ukraine's cities. Russian soldiers would simply walk across the bridge that marks the border or wade through the Narva River. Narva is located directly across that river from its sister city in Russia, Ivangorod. The two cities’ medieval fortresses are visible from each other. Narva's Hermann Castle is literally a stone's throw away from Ivangorod.

To make the action seem less like an invasion, to forestall a robust NATO reaction and seek to divide the alliance, Russia might foster a “Russian popular front,” infiltrate “little green men” (soldiers without insignia), and stage a referendum for union with Russia, as it did in Crimea.¹¹⁷ But what if NATO did respond by invoking Article 5 of the North Atlantic Treaty? It proclaims that “an armed attack against one or more of them in Europe or North America shall be considered an attack against them all” and that measures include “the use of armed force.”¹¹⁸ What defense would be possible for a town so vulnerable to overwhelming Russian force?

Here the historical example of Berlin is relevant. NATO's plan to defend Narva by offering the U.S. nuclear umbrella as extended deterrence amounts to the same threat that the United States used to defend the isolated West Berlin outpost. The idea was to deploy a limited contingent of forces as a tripwire and threaten escalation to nuclear war if they were challenged.¹¹⁹ It was a threat of dubious credibility and potentially disastrous outcome, even if the common wisdom declares West Berlin a success story of nuclear deterrence. As Schelling writes:

There is a problem with applying incorrect lessons of the Cold War to the current situation of vulnerable NATO territories such as Estonia. Nuclear deterrence was not tested in Cold War Europe, because the Soviet Union did not intend any of the aggressive actions that NATO feared. So it is wrong to claim that deterrence worked then and will work to defend NATO countries and even Ukraine after the current war. What is known about nuclear weapons—from research into the Soviet archives, for example—is how much they heightened the danger of inadvertent war. That danger persists. Moreover, with Putin in charge, NATO's effort to defend its territories on Russia's border by threatening nuclear escalation courts disaster. Putin might well consider it a bluff.¹²¹ He is more risk-prone and aggressive than the cautious leaders who ruled the Soviet Union during the Cold War.¹²² This does not seem the time to reinstate the questionable security policies of that era, but rather to reconsider them and the alternatives that were proposed in the 1980s. But NATO seems locked into Cold War concepts such as tripwires and extended deterrence. The forces that it deploys in Estonia, Latvia, and Lithuania, for example, are described by some observers “not as directed toward stopping a Russian invasion of a Baltic NATO member, but instead as a tripwire to provoke American involvement,” with the implicit threat of escalation to nuclear war.¹²³

That Putin or anyone else might call NATO's bluff and expose the fragility of nuclear deterrence should lead to a rethinking of reliance on such strategies. Some analysts—and, presumably, state leaders—nevertheless have reinforced their commitment to nuclear weapons, seemingly embracing the views of Kenneth Waltz and John Mearsheimer that nearly every state can achieve security by obtaining nuclear weapons.¹²⁴ They point to Ukraine as an example: if only the country had kept its Soviet-era arsenal, the argument goes, Russia would never have invaded. But had Ukraine kept the Soviet nuclear weapons, it would have required considerable time and effort of Ukrainian specialists to maintain the weapons and to make them suitable for attacking Russia, given their technical configurations and targeting capabilities. Ukraine's insistence on keeping the Soviet nuclear weapons would not have magically produced an instant deterrent. It would more likely have led to a prolonged period of instability and conflict with Russia, even under Yeltsin's government, and to rogue status as a country that rejected prevailing norms on nuclear nonproliferation.¹²⁵

Instead of advocating nuclear proliferation as the solution to the inadequacies of nuclear deterrence, some suggest returning to proposals that date to the Cold War. These proposals range from strategies and weapons to make nuclear deterrence more credible by lowering the threshold for their use to what has variously been called minimum, minimal, or finite deterrence. Deploying tactical nuclear weapons on the frontlines of potential European battlefields is more likely to lead to unintended nuclear escalation than to reliable deterrence.¹²⁶ Some critics highlight the likelihood of miscommunication and the risks of unintended escalation mitigated only by luck—conditions that still prevail and that would affect any proposals for enhancing credibility by deploying “small” nuclear weapons.¹²⁷

Proponents of minimum deterrence are less enthusiastic about nuclear weapons than those preoccupied with enhancing credibility by making nuclear use more likely. The former propose limiting use of nuclear weapons to a retaliatory strike against a country that has already attacked one's own country with nuclear weapons. Minimum deterrence would, in that respect, seem incompatible with the extended deterrence that the United States promises to its allies—because it would not ensure U.S. nuclear retaliation for actions short of a Russian nuclear attack.¹²⁸ Moreover, as the widespread support for the Nuclear Ban Treaty indicated, many countries and people reject a policy that relies on the threat of indiscriminate slaughter of civilians as a means to security. Not surprisingly, for people who hold that view, the Russian aggression against Ukraine, Putin's nuclear threats, and the dangerous pursuit of military operations around vulnerable nuclear power facilities have redoubled their advocacy for a nuclear-free world. Their understanding of nuclear deterrence echoes the deadly connections critique of the Cold War. As Rebecca Johnson puts it, “far from deterring war, nuclear possession encourages reckless military behaviour that ignores real-world dangers and enables certain leaders to believe they can deter others while enjoying freedom of action and impunity for themselves.”¹²⁹

There is no obvious way for nuclear deterrence to prevent Russian encroachments on nearby territories, regardless of whether they are members of the NATO alliance. Referring to the “nuclear umbrella” of U.S. extended deterrence, Newt Gingrich, former speaker of the U.S. House of Representatives, said in 2016: “Estonia is in the suburbs of St. Petersburg … I'm not sure I would risk a nuclear war over some place which is the suburbs of St. Petersburg.”¹³⁰ A careful analysis by two Baltic security specialists, published in 2017, also concludes that a policy founded on “deterrence by punishment” of Russian aggression would likely fail and divide the alliance. They favor “deterrence by denial,” which relies on both the conventional military capabilities deployed by NATO's Enhanced Forward Presence (eFP) multinational combat groups and less tangible factors, such as “political and societal readiness and resilience.”¹³¹ They argue that “NATO eFP units stationed in the Baltics can be a ‘speedbump,’ but their value is largely political, acting as a tripwire”—again that discredited Cold War concept—“that would ensure a larger response from NATO should they be attacked.”¹³² The key is not to have that “larger response” look like the one NATO envisioned to “defend” West Berlin in 1961—that is, a major nuclear war.

The most reliable way to prevent the Ukrainian war, or any future European war, from escalating to a nuclear holocaust is for the states armed with nuclear weapons to commit not to use them and to keep that commitment. Putin obviously has done the opposite with his frequent nuclear threats. The United States and its NATO allies, still beholden to extended nuclear deterrence in their own security policies, missed an opportunity to stigmatize his actions as illegal. The Nuclear Ban Treaty (Article 1d) criminalizes not only the possession of nuclear weapons but also the threat of their use. The UN Charter (Article 2.4) itself requires that states refrain from “the threat or use of force” against the territory of other member states. In the words of Pavel Podvig, “Politicians, experts, journalists, and citizens should not get into discussions about what kind of nuclear weapons could be more or less effective from a military or political point of view” to counter Putin's nuclear threats. “The very thought of nuclear weapon use should be condemned as irresponsible and criminal.”¹³³ Keeping nuclear weapons off the table, in compliance with international law, is essential to preventing a nuclear war. As Ukraine demonstrates, non-nuclear alternatives for defense against even a nuclear-armed aggressor are possible.

In the wake of Russia's 2022 invasion, some U.S. and European specialists are revisiting the ideas that animated peace researchers’ efforts during the 1980s to go beyond nuclear deterrence as a source of security. These proposals are intended to dampen the dangerous spiral gripping Russia and NATO and to shift the dynamic to a conventional deterrence model. To provide defense and lower the risk of nuclear escalation, they propose “confidence-building defense,” consisting of local defensively oriented forces backed up by mobile units behind the front lines.

The approach builds on the historical generalization that defense requires fewer forces than offense, but it also considers the impact of force posture—the benefits of using lighter, dispersed forces as opposed to massed operations that would be vulnerable to long-range precision strikes, even non-nuclear ones.¹³⁴ In addition, confidence-building defense fosters stability in two ways. First, it “embodies little or no capacity for large-scale or surprise cross-border attacks.” Second, it “provides few, if any, high-value and vulnerable targets inviting an aggressor's attack.”¹³⁵ Although such an approach would not provide a panacea for the hardest type of security challenge, such as Narva, it seems superior to the alternatives and more promising than one that relies on a tripwire to nuclear destruction.

An earlier proposal for a non-nuclear Ukrainian defense strategy—drafted by Barry Posen in 1994 and originally published in Russian—resembles a confidence-building defense and lends support to its plausibility. Posen developed a plan for “strategic defense in depth,” loosely based on the territorial defense strategies of countries such as Finland, Sweden, and Switzerland, and drawing on the lessons of World War II. He took account of the security dilemma and the goal of providing for Ukraine's defense without posing a threat to its neighbor: “Though Russia may complain about any military planning directed against her,” he explained, “this particular plan is about as ‘defensive’ as one can get within the realities of armored warfare.”¹³⁶ Many of the plan's factors that Posen noted could present difficulties for Ukraine have been resolved since the 2022 Russian invasion: the commitment of Ukrainian soldiers to their country's defense; Ukraine's dependence on Russian energy sources; support from Ukraine's neighbors to the West (not yet members of NATO at that point); and Ukraine's ablility to acquire or produce additional arms beyond its current stockpile. If Ukraine emerges from the war with much of its territory intact and the continued support of the United States and its NATO allies, its prospects for conventional defense against future threats should be even greater than what Posen envisioned in 1994.

A non-nuclear Ukrainian security strategy could also include nonmilitary means of defense, what the Baltic authors call “political and societal readiness and resilience.”¹³⁷ Research on civilian-based resistance to invasion and occupation, dating to the work of April Carter, Adam Roberts, Gene Sharp, and others in the 1960s and 1970s, and reflected in the proposals of the British Alternative Defence Commission and others in the 1980s, has expanded considerably owing to the work of Erica Chenoweth and colleagues.¹³⁸ Scholars show how civilian resistance played a role in overthrowing the regime of Viktor Yanukovych in 2014 and in potentially thwarting Russian war aims by undermining the occupation of Ukrainian territory.¹³⁹ Even during the Soviet era, researchers credit Czechoslovakia's uncoordinated nonviolent popular resistance to the 1968 Warsaw Pact invasion with preventing the Soviets from consolidating control for the better part of a year.¹⁴⁰

Strategies of civilian-based, nonviolent resistance are demanding and require a high level of societal commitment and solidarity.¹⁴¹ They are harder to execute in regions where people might not trust one another or their government—a plausible description of areas of the Donbas and Crimea before the Russian interventions of 2014, and the reason the governments of the Baltic states, Kazakhstan, and Moldova should prioritize making their Russian-speaking populations feel fully accepted as citizens.

When faced with an unscrupulous army determined to extract resources from the occupied territory, nonviolent resistance would prove especially difficult.¹⁴² Civilian resistance—even nonviolent—could also blur the distinction between combatant and noncombatant and encourage the occupier to violate norms of civilian immunity. If, however, the scale of resources for military spending were redirected to fostering the self-reliance and social trust necessary to underpin civilian resistance, along with advance planning, even authoritarian figures like Putin might pause before undertaking aggressive military action. Researchers have already devoted considerable attention to tracking the hundred-year history of nonviolent Ukrainian resistance to colonial rule and mapping the actions carried out since the February 2022 Russian invasion.¹⁴³ Strengthening civilian resistance as a component of Ukraine's security strategy constitutes a promising alternative to extended nuclear deterrence.

For vulnerable outposts such as Narva, neither a nuclear tripwire nor confidence-building defense could guarantee its security against a determined Russian effort to seize the city. Making the city ungovernable by an occupying army could serve as a deterrent. To do so, the Estonian government would need to make its Russian citizens feel more committed to Estonia than to the declining Russian police state to its east—a task that requires addressing Russians’ sensitivity to linguistic discrimination and malaise associated with a deindustrialized economy.¹⁴⁴

The Ukrainian case for a non-nuclear, confidence-building strategy is more plausible. Regarding the inward-facing element of confidence-building, the Russian invasion fostered a coherence and national sentiment that the fragile Ukrainian democracy, riddled with corruption and polarized politics, had been lacking. Ukrainians have come together to defend their territory. The outward-facing element would be intended to instill confidence in Russia that Ukraine's armed forces would not pose an offensive threat. This element was especially important for alternative defense proponents during the Cold War, when both sides supported the status quo and a strictly defensive orientation could alleviate the security dilemma. Although post-Soviet Russia rejected the status quo when it intervened in the Donbas and annexed Crimea in 2014, there is still a role for confidence-building. Especially if the Ukrainian war ends with a territorial compromise short of full liberation of the lands seized in 2014 and 2022, an enduring peace will depend on Russia's confidence that Ukraine will not stoke irredentist claims backed by an offensive capability to pursue them.

What would a confidence-building defense for Ukraine entail? A plan put forward by Lutz Unterseher for defense of Germany in the 1980s is typical of the proposals of that era and could be adapted to Ukraine's situation. It included three elements: First, a decentralized infantry network, called the commitment force, provides “a static area defense that uses reactive ‘wait and see’ tactics.” Second, a rapid commitment force comprises “mechanized troops with a certain degree of operational mobility that conduct reactive and active missions.” Third, a rear protection force includes “light infantry for object defense and motorized/light armor units to deal with airborne assaults and large-scale diversion.”¹⁴⁵ Up to 90 percent of the rear protection force would consist of reservists, based on a regional mobilization plan, whereas the forward zone of decentralized infantry would be staffed by active-duty personnel. The Ukrainian reserve force should prove particularly potent, given the army's considerable experience in combat against Russians, although its troops have suffered many casualties in the Russo-Ukrainian War.

Technological advances in sensors and precision-guided munitions and drones should entail changes in the 1980s-era conceptions, but confidence-building defense for Ukraine is still a work in progress. The key concept is known as “spider in the web.” It has four main tasks: “To delay and wear down invading forces; to provide communications links and most of the information for the mobile troops; to provide physical and electronic coverage for the mobile forces, that is, artificial obstacles to protect them and electronic jamming to make them harder to find; and to support the mobile elements logistically, resupplying them from numerous camouflaged decentralized storage sites.”¹⁴⁶ In a 2022 War on the Rocks piece, the authors explain that “the web would be made up of a network of dispersed infantry units, equipped with modern weaponry like light artillery and shoulder-mounted anti-armor rockets capable of delaying and progressively wearing down invading forces.”¹⁴⁷ The “spider” would consist of mobile combined-arms armored units. They would provide “the strike and shock to destroy the enemy's momentum and confidence” and undermine its “achievement of strategic objectives.”¹⁴⁸ To dampen any security dilemma dynamics during a crisis short of war, “the armored component would not be large enough, nor would it have the logistical capabilities, to conduct offensive operations outside the web.”¹⁴⁹ With the emphasis on providing no pretext for a postwar Russia to reignite the war, the spider-in-the-web defense is compatible with Posen's 1994 plan and the principles of confidence-building defense in general.

Aside from the use of animal metaphors, the spider-in-the-web defense shares some elements with Franz-Stefan Gady's proposal to turn Ukraine into a “bristling porcupine.” As he describes, “an ideal porcupine strategy is built around the assumption that the defender's sharp quills can inflict enough pain on the attacker to convince him that he will not attain his goals on the battlefield.”¹⁵⁰ Ukrainian forces, although not necessarily more numerous than Russian ones, would be designed such that “any attack would meet continuous ambushes, counterattacks, and hits by long-range artillery and missiles. Then, when the attacking Russians are already severely depleted, the bulk of Ukraine's well-armed, well-trained force would push back or destroy the invaders. It is a porcupine strategy with a hammer blow at the end.”¹⁵¹

Gady's proposal incudes long-range weapons, such as air-launched cruise missiles, that a confidence-building approach would eschew because of their offensive potential. Another drawback to the porcupine strategy is that it would require Ukraine to maintain a high level of militarization, “keeping its economy on a war footing to produce arms, raise weapons technology to a NATO standard, and otherwise sustain a formidable military over the long term.”¹⁵² This could also be true of the confidence-building defensive strategy, although its emphasis on reserve forces should decrease costs. Moreover, it is possible that the nonprovocative nature of the approach would facilitate a long-term peaceful settlement. After all, even Alsace-Lorraine—long a casus belli for two determined adversaries—eventually contributed to cooperation in the form of the European Union.¹⁵³

There are several counterarguments to the confidence-building approach. Some critics might be relucant to forgo Ukraine's NATO membership and give up the nuclear umbrella. In effect, they might argue that the nuclear risk is worth taking—or even necessary—to defend Ukraine. Others might suggest that the war shows the power of conventional forces on the defensive, and the effectiveness of armies operating in traditional ways, with sufficient equipment and adequate size. According to this view, continued Western aid tips the conventional balance in Ukraine's favor and negates the need to redesign Ukrainian or NATO defense to the degree required by the alternative strategies—especially when the Russian army has conducted itself so poorly in the Russo-Ukrainian War.

Presumably the United States and its NATO allies would continue to support postwar Ukraine, even in the absence of NATO membership, including by providing arms and training. But, as Gady points out, a “status of de facto integration into the alliance short of an Article 5 guarantee could be the worst of both worlds for Kyiv: It could trigger further Russian escalation while leaving Ukraine uncertain about the precise military support it would receive in case of war.”¹⁵⁴ Moreover, it is uncertain whether external support for Ukraine will continue at current levels, much less increase over time. This is a particular concern after the fighting ends. Other states are likely to perceive a cold war between Russia and Ukraine as less threatening than a hot one. Economic problems might force supporters to restrict their funding to Ukraine. Western European countries and the United States might reassess their interests in Ukraine sooner rather than later, leaving Ukraine to marshal what limited support it can in the face of any new Russian threat.

Confidence-building defense allows Ukraine to depend on its own resources and to integrate whatever support other states are willing to provide, so long as it does not provoke Russia to resume the conflict. The main point is to sever the connection between Ukraine's defense and potential escalation to nuclear war. That could happen if Ukraine remained outside NATO and the U.S. nuclear umbrella, or if NATO—with or without Ukraine as a member—favored an alliance-wide shift to conventional defense and deterrence rather than nuclear deterrence. Such a shift is conceivable, given that some old and new alliance members are skeptical of nuclear weapons (e.g., Finland, Norway, Sweden), and that nuclear use on the continent could destroy what it is intended to save. At the end of the Cold War, Europe came close to full denuclearization.¹⁵⁵ It was a missed opportunity that should be reconsidered.

So many unexpected developments have occurred since February 2022 that making confident predictions about the future seems questionable. The brazen Russian attack, although intelligence reports accurately predicted its preparations, still seems incredible. Most observers were surprised by Ukraine's coherent and steadfast response, the military's effective defense, and the solidarity offered by NATO members. Russia's brutal and deliberate destruction of civilian property and life was less surprising.¹⁵⁶ That the historically neutral Nordic countries of Finland and Sweden would react with decisions to join NATO was, for many, unexpected, although they had been moving toward closer collaboration with the alliance for decades.¹⁵⁷ Their NATO membership could bolster the alternative policies described here. Both countries have eschewed pursuing nuclear weapons and both have relied on systems of territorial defense with limited offensive capabilities to provide security.¹⁵⁸ States such as Poland and Romania that joined NATO in the 1990s had earlier advocated territorial defense as part of their military traditions, but the alliance had discouraged it in favor of military specialization by country.¹⁵⁹ Perhaps with support of the new Nordic allies, such interests might attract NATO's attention as it seeks to contend with Russia's potentially aggressive designs on its members.

No one knows what borders a postwar Ukraine will need to defend, nor what degree of hostility or chaos will emanate from its neighbor to the east. In an earlier period of instability, as the Cold War ended and the Soviet Union disintegrated, leaders sought to limit the role and numbers of nuclear weapons and drastically reduce and restructure conventional armed forces. European security in the wake of Russia's invasion of Ukraine is more perilous now than it was then. The nuclear arms control regime is in a shambles, making it senseless to stake Europe's defense on weapons of mass destruction.

Whether NATO's expansion created a self-fulfilling prophecy of Russian aggression or anticipated the inevitable will continue to be debated. But the security threat from Russia is indisputable, and how to counter it demands increasing attention from scholars and practitioners. Reasserting the role of nuclear weapons to try to enhance extended deterrence would be a dangerous mistake. A better alternative would be to revive the promising proposals of the late Cold War for a non-offensive defense system that provides neither suitable targets for nuclear attack nor a pretext for renewed Russian aggression.

The author presented an early version of this paper at the 21st Annual Aleksanteri Conference, “The New Era of Insecurity: How Russia's War in Ukraine Changes the World,” Helsinki, October 26–28, 2022, and is grateful to the other participants for their reactions. For valuable comments on subsequent drafts, the author thanks Ulrich Kühn, Lukas Mengelkamp, Agnieszka Nimark, Benoît Pelopidas, Pavel Podvig, Henry Shue, and Rebecca Witonsky.