Russia’s Invasion of Ukraine and NATO’s Crisis of Nuclear Credibility

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For decades, Americans and Europeans did not have to think about the dynamics of large-scale warfare between great powers or the possibility of nuclear escalation. Russia’s unprovoked invasion of Ukraine has shattered that sense of security.

What’s more, the invasion of Ukraine, and the rhetoric surrounding it, has revealed the scope of Vladimir Putin’s grand ambitions: He wishes to reconstitute as much of the old Russian/Soviet empire in Eastern Europe as he can. The delegitimization of Ukraine has thrown into doubt the legitimacy of former Soviet republics Latvia, Lithuania, and Estonia and even neighboring states such as Finland and Poland. Putin regards the collapse of the Soviet Union as the “greatest geopolitical catastrophe of the century” and laments that it caused “tens of millions of our fellow citizens and countrymen to live beyond the fringes of Russian territory.” Putin feels that in order to be secure, Russia needs to revise the current balance of power in Europe. This ambition is consistent with scholarship that explains Russian foreign policy as a product of Putin’s illiberal, conservative philosophy and Putin’s desire to develop a Russian sphere of influence in the post-Soviet space.



In the long run, the best way for NATO to deter him is to have enough conventional forces in Eastern Europe to deny Russia the ability to take the territory of countries such as Latvia, Lithuania, Estonia, and Poland. But NATO does not have the capability to do this at the moment, and it will take time to develop it. In the intervening “window of vulnerability,” the American extended nuclear deterrent and NATO’s tactical nuclear weapons will form the backbone of European security.

The best way to ensure the credibility of this deterrent depends, in turn, on the outcome of the current war. If, as appears likely, Russia gets bogged down in a long drawn-out fight in Ukraine, it may have an incentive to expand the conflict by attacking an Eastern European NATO country. To deter this, the United States and NATO should increase the credibility of their nuclear deterrent by embracing a moderate form of the brinkmanship tactics articulated by an earlier generation of nuclear strategists. This would entail altering America’s and NATO’s nuclear posture such that it threatens to use its nuclear weapons earlier in a conflict. This solution is not ideal and should only be regarded as a short-term fix, but European security today requires NATO to accept a degree of brinkmanship.

Risk to the Baltics

The goal for the United States and its NATO allies should be to protect Eastern European countries such as Latvia, Lithuania, Estonia, and Poland from a Russian attack. Eastern European NATO countries, especially the Baltic states, do not have the capabilities to do this on their own. The Russian military is performing poorly in the initial phase of the war in Ukraine, but this should not be taken as evidence that NATO countries in Eastern Europe have adequate capabilities for conventional defense. Indeed, these countries may fare worse against a Russian invasion than Ukraine has done, as their militaries are smaller than the Ukrainian military. Plus, the Russian operation in Ukraine appears to have been informed by wildly optimistic assumptions that the Ukrainians lacked the will to put up a fight and that resistance would crumble in short order. This could be why the first phase of the Russian invasion used only a fraction of the 190,000-strong force it amassed around Ukraine. The United States and NATO should expect that a Russian attack on a NATO country would have different assumptions and go differently, perhaps with Russia using many more of its forces in the opening phase of the campaign.

Many Russian forces are bogged down in Ukraine, but Russia still has the conventional strength to expand the current war into NATO territory. For example, Russia could leverage its strength in conventional long-range strike to attack convoys of supplies going into Ukraine. Indeed, this is something that Russia has recently threatened to do. Furthermore, Russia could try to hold territorial gains in eastern and southern Ukraine instead of fighting offensive missions to take more territory. A new “defensive” focus in Ukraine could free more Russian forces for an attack on an Eastern European NATO country. In short, Russia still has the capability to conduct strikes against NATO allies and to turn the focus of its combat power on them should it choose to do so.

After Russia’s invasion of Ukraine, European NATO allies are now likely to increase investments in their armed forces that could make a successful conventional defense possible in the future. Germany’s decision to double its defense budget is telling in this regard. NATO’s increase in troops deployed to Eastern Europe is also a positive recent development. But these developments will take time to bear fruit.

Currently, NATO’s defense of the Baltics hinges on the threat of responding to a Russian attack with its nuclear arsenal. But Putin’s recent nuclear saber-rattling suggests he may not find this threat credible and believes Washington will back down rather than risk nuclear war. Indeed, even during the Cold War, it was difficult enough to convince the Soviet Union that the United States would trade Berlin for Boston. Expanding the alliance has only heightened this challenge. How can the United States make Putin believe that it is willing to trade Vilnius for New York?

The Art of Brinkmanship

In response to this challenge, the United States and NATO should embrace the paradox of brinkmanship, which involves trying to prevent war by making it hard to contain once it starts. In the words of Thomas Schelling, “by arranging it so that we [the United States] might have to blow up the world, we would not have to.” This involves making “threats that leave something to chance,” or threats that, once enacted, would “initiate a process that may quickly get out of hand.”

States use tactical nuclear weapons to bid up the shared risk of nuclear escalation in the event of a war. Because tactical nuclear weapons are less destructive than “strategic” nuclear weapons, they are seen as more usable and blur the firebreak between conventional and nuclear war. At the same time, the use of tactical nuclear weapons generates a higher risk of general nuclear conflict than does the use of conventional forces, meaning that threats to use tactical nuclear weapons early in a war increase the shared risk of disaster. This is why states who face conventional inferiority tend to invest more heavily in these weapons.

Brinkmanship tactics also involve a trade-off between deterrence and the risk of escalation. A state could employ a “minimal brinkmanship” strategy that generates low risk of nuclear use, and if the state lacks the conventional strength to deny the adversary its objectives in a war, this could incentivize the adversary to attack. On the other hand, a state could enact a “maximum brinkmanship” strategy that generates high risk for nuclear war in the event of a conflict, but that high risk could generate restraint on the part of the adversary. The United States used a form of maximum brinkmanship in the 1958–59 Berlin Crisis by threatening escalation to nuclear use very early in a war over Berlin. As one of Daniel Ellsberg’s colleagues described that strategy to him: “We send in a series of increasingly larger probes. If they’re all stopped, we fire a [nuclear] warning shot. If that doesn’t work, we blow up the world.”

The degree of brinkmanship in a state’s defense strategy lies on a scale from the minimum to the maximum end. Where a state’s strategy should fall on the scale depends on the adversary’s intentions and capabilities. Against an adversary with conventional inferiority, it makes little sense to run a higher risk of nuclear war. For an adversary with aggressive motivations, the risks of maximum brinkmanship may be justified. However, if an adversary is not planning on using force, a maximum brinkmanship strategy could make them feel insecure and prompt them to launch the attack that the state was attempting to deter.

Brinkmanship in the Baltics

What kind of adversary does NATO face in Moscow? The answer depends on the outcome of the current conflict. Based on current developments, it seems all too likely the result will be an aggravated Russia that is stuck in a grinding war in Ukraine. After six weeks of fighting, the Russian advance in Ukraine has stalled. This slow progress has prompted Russian forces to resort to horrific indiscriminate violence against civilians in these areas. At this moment, a quick victory toppling the Ukrainian government and leading to an emboldened Russia looks unlikely.

At the same time, Russia is unlikely to accept defeat in Ukraine anytime soon. Reports came out on March 29 that Ukraine and Russia were making progress on peace talks, but Russia’s lead negotiator Vladimir Medinsky stressed that there was “still a long way to go” before Russia would agree to a ceasefire. Instead, Russia appears to have changed its war aims from taking Kyiv to consolidating control over eastern Ukraine. Fighting for this objective is likely to be costly and raises the probability that this war will be a protracted conflict. Western sanctions against Russia will remain in place during the war, and Western countries will continue to provide assistance to Ukrainian armed forces. That assistance will flow through Eastern European member states.

To break out of a stalemated war and achieve victory, Putin could try to target supplies in transit while they are still in an Eastern European NATO country, especially Poland. Putin could also conduct a limited attack against a Baltic State in order to take territory that is majority Russian-speaking. That could bolster his claim of defending Russian speakers abroad. He may be incentivized to do this if the economic sanctions prove too harsh on the Russian economy, and he sees no way out of the crisis except by expanding the war. That pathway to escalation is similar to Imperial Japan’s rationale for attacking Pearl Harbor in 1941.

This scenario poses a serious test for deterrence for NATO. A strike on supplies going to Ukraine would be difficult to defend against, and Russian forces could overwhelm the NATO forces assigned to an initial defense of the Baltics. The best response to the threat of these scenarios is to prevent them from happening in the first place. To do that, a modest degree of brinkmanship could prove effective. Here, the United States and NATO should alter their nuclear posture and declaratory policy to allow for asymmetric escalation.

The alliance already has B61 gravity bombs deployed across five countries in Europe and deliverable by dual-capable aircraft. The United States and NATO can enhance their impact by changing the Nuclear Posture Review and the Deterrence and Defence Posture Review to stress that they reserve the ability to use nuclear weapons first. In addition, the aircraft units assigned to carry NATO’s nuclear weapons can hold more exercises to emphasize the operational readiness of those forces. If an attack by Russia looks imminent, the United States, in consultation with NATO allies, can put those forces on alert. The goal of these steps by the United States and NATO would be to emphasize to Russia the nuclear implications of an attack on a NATO country without taking steps that could cross a Russian “red line” and provoke it.

What is important here is not making sure that NATO has more tactical nuclear warheads than Russia or that they are able to stop a Russian advance on their own. NATO’s nuclear weapons would primarily have a political effect: threatening a breach of the nuclear threshold. The current arsenal of around 130 tactical nuclear weapons should be sufficient for that task.

Such an asymmetric escalation strategy is not ideal and carries great risks, but it is a product of past decisions to expand NATO without first developing real plans for the defense of new members. NATO expansion came at a time when policymakers assumed that the risk of war in Europe was low and thus did not have to think about the dynamics of great power war or escalation. Putin has disabused Western leaders of their naïveté and in the process shown himself to be aggressive and risk-acceptant in the pursuit of ambitious goals. Threatening early nuclear use in a NATO-Russia conflict may be the best way to protect Europe from Putin’s recklessness.



 Tyler Bowen is a postdoctoral fellow in the Kissinger Center at Johns Hopkins SAIS. His research focuses on the dynamics of nuclear crisis bargaining and the implications of those dynamics for U.S. grand strategy. More information on his research can be found at, and you can find him on Twitter @RealTylerBowen


Image: 1st Lt. Johnathan Carkhuff, Air Combat Command Public Affairs