Recent nuclear saber rattling by Russian President Vladimir Putin is forcing the West to confront a question that even many national security professionals have been able to ignore for decades: Would Putin actually use tactical nuclear weapons? More specifically, would he order a tactical nuclear strike on Ukrainian military forces out of frustration that his military forces have failed to achieve their objectives? Assessing that possibility requires a reevaluation of certain assumptions that is long overdue.

Russian Nuclear Weapons, in Context

In the current context, Putin could view nuclear weapons use as necessary to ensure Russian national security interests are not derailed by overt Western military support to Ukrainian efforts—which would be in line with stated Russian doctrine. One course of action could be a so-called demonstration strike with a single low-yield nuclear detonation in Ukraine or over the Black Sea to serve as a dramatic warning that resistance to Russia’s military campaign must be ended, backed by the compellent threat of further tactical nuclear attacks. There is no question that Putin has already signaled the use of nuclear weapons as an option, and he has stated his (alleged) concern about nuclear weapons being stationed in Ukraine for use against Russia.

Aside from the question of whether a Russian nuclear strike is credible as an aspect of future military operations in Ukraine, there are ample reasons that prudent policy must consider the threat of Russian nuclear weapons use as credible. First, Russia does not have a “no first use” policy and has doctrine to use nuclear weapons in the event that it was losing a conventional conflict with NATO forces. A nuclear attack against Ukraine would be intended to allow Russia to conclude a regional conflict on terms acceptable to its leadership. Second, Russia under Putin has made significant investments in nuclear weapons modernization and has frequently exercised its nuclear forces. Third, Putin has stated his concern over Ukraine developing a nuclear “dirty bomb” as well as the “aggressive statements” of NATO powers. These false statements could be intended as establishing a casus belli to use a tactical nuclear weapon. On the other hand, this might be merely a case of nuclear brinksmanship that will not play out in Russia’s favor.

It is true that the Russian Federation did join the other four states designated by the Nuclear nonproliferation Treaty as “nuclear-weapon states” in a joint statement that affirmed “a nuclear war cannot be won and must never be fought.” However, it is important to clarify that this statement does not represent a general call for disarmament or an assurance that nuclear weapons will never be used. It reflects the five nuclear-weapon states’ view that their continued sustainment of nuclear weapons serves as the basis for ensuring that a nuclear war—between nuclear states—will not be fought, rather than a moral condemnation of such a war. Russia has nearly two thousand tactical nuclear weapons and continues to modernize this capability, perhaps as a measure intended to augment its (demonstratively deficient) military forces as it develops more capable advanced conventional munitions. Clearly, Putin has defined a role for nuclear weapons within his worldview, and at the same time, Western politicians and strategists have not engaged the possibility of nuclear weapons being used in contemporary conflicts.

Flawed Assumptions

The Russian incursion into Ukraine has caused a flurry of commentary by nuclear weapons experts on Twitter as to the implications of a potential nuclear strike. These views are valuable and well worth reading to understand the deterrence dynamics in this scenario. At the same time, there are general national security analysts who are fixated on a number of hypotheses that are based in Cold War thought. Notable among them: that there is no such thing as a tactical nuclear weapon because all nuclear weapons are strategic; that any use of a nonstrategic nuclear weapon would inevitably lead to a full-scale nuclear war; and that Putin must be insane to think he could employ nuclear weapons in Ukraine and not face nuclear retaliation.

Let’s take these one at a time. The first assumption, that there is no such thing as a tactical nuclear weapon, is simply wrong and based more on emotional feeling than rational assessment. It is a function of how we define “tactical” and “strategic” and implicitly assumes that the detonation of any nuclear weapon, no matter the yield, would have a strategic effect. And of course any nuclear weapon event would have a strategic political effect, rippling throughout the international community. But strategic effects don’t only come from strategic weapons. There is a difference between nuclear weapons delivered by strategic military forces (missiles, bombers, and submarines) against a nation’s critical infrastructure and nuclear weapons delivered by operational military units in a theater of operations against adversarial military forces.

We know that there are nonstrategic nuclear weapons because the US and Russian governments clearly define a subset of weapons and forces as strategic nuclear forces—land-based missiles with ranges over 5,500 kilometers, modern submarine-launched ballistic missiles, and heavy bombers. Anything not so defined falls under “nonstrategic nuclear forces.” The Russian Federation further defines tactical nuclear weapons as those “designed to engage objects in the tactical depth of enemy deployment (up to 300 km) to accomplish a tactical mission.” We can call these nonstrategic weapons, theater weapons, or tactical weapons, but it all falls out the same.

The US military has gone back and forth over the utility of tactical nuclear weapons since the beginning of the Cold War, and the debate continues today. The 2018 Nuclear Posture Review report called out the requirement for a low-yield nuclear weapon as a deterrent against Russian tactical nuclear weapons use. The US Air Force is developing a “conventional-nuclear integration” concept that calls for theater forces to consider limited nuclear strikes during conventional combat operations against a nuclear-capable adversary. In recent testimony to the Senate Armed Services Committee, Admiral Charles Richard, commander of US Strategic Command, noted that his command “has been preparing. . . for years along with other combatant commands” for scenarios that included “limited nuclear use in a conventional aggression scenario.” He noted, “There is a significant class of theater threats that we’re going to have to rethink potentially how we deter that.” One starting point is accepting that tactical nuclear weapons constitute a threat to US conventional superiority that may not be deterred by the blunt instrument of strategic nuclear forces.

The second assumption, that any use of a tactical nuclear weapon would inevitably cascade toward a strategic nuclear exchange between Russia and the United States, is a hypothetical left over from the Cold War. Models of escalation examine the process by which two peer competitors would move from conventional to nuclear warfare in the course of a direct conflict. Can a nuclear-weapon state dictate the pace of a crisis with another nuclear-weapon state and anticipate its adversary’s reactions, while avoiding a total war strategic exchange? It’s a theoretical construct that has not been tested. The Russian concept of strategic deterrence focuses on “escalation management,” which uses both military and nonmilitary measures to shape an adversary’s decisions. This is a different concept than US strategic deterrence theory, which relies on “calculated ambiguity” to cause doubt in the adversary’s mind as to future US actions.

A Russian nuclear attack on Ukraine would not directly target US or NATO forces, although certainly it would be a direct signal to nations supporting Ukraine’s conflict. Consider a scenario in which Russia detonates a low-yield (e.g., less than five kilotons) nuclear weapon as an airburst over a Ukrainian mechanized brigade outside of Kyiv. As a result, the long-term effects of fallout are avoided. Because Ukraine is not a member of NATO, there is no immediate trigger for a NATO retaliatory strike. The US government has no extended deterrence promise with the Ukrainian government. Would this singular event lead toward a strategic nuclear exchange? Would the United States trade New York City for Kyiv, to paraphrase General Charles de Gaulle? The Obama and Trump administrations had different approaches to exercises involving a Russian limited nuclear strike. At the least, there would be significant consequences that might include an increased US military presence in Europe, additional flights of US strategic bombers to Europe, as well as new diplomatic and economic sanctions against Russia. But it’s difficult to see how a limited nuclear strike in Ukraine leads to a total war scenario.

The third assumption centers on Putin’s rationality and the question of whether he would actually use tactical nuclear weapons, breaking the international taboo on their use. In particular, one might question Putin’s rationality in light of his eyebrow-raising claims that Ukraine was developing a WMD program, that its government was run by fascists, and that it was committing genocide against ethnic Russians in the Donbas. This view of his public statements misses the point of rational actor theory regarding state decisions involving nuclear weapons. A rational decision maker is one that examines the available information and makes a decision based on what course of action provides the greatest benefit, ideally at a lower cost than other options.

If Putin is a rational actor, could he still consider a limited nuclear strike as part of his plans? He may believe that this is a rational act if he sees some advantage toward accomplishing the goals of overcoming Ukrainian resistance, keeping NATO out of the conflict, and ultimately restoring Russia’s past glory. But he does still have time to play out other options—cutting off electrical power, food, and medical supplies to Ukraine’s cities, increasing attacks against civilian infrastructure, or just continuing to use his conventional superiority over Ukrainian forces (despite current setbacks). If conventional options fail, he may then reach to tactical nuclear weapons as a way to meet his political objectives. So yes, a rational actor could consider using a nuclear weapon against a nonnuclear adversary.

We Need to Talk About Tactical Nuclear Weapons

Given this information, it remains unclear whether Putin might order a limited nuclear attack—for instance, a single airburst with a low-yield warhead. But if he did, would the United States be prepared to respond? Admiral Richard’s recent testimony to Congress suggests that US Strategic Command has had a lot of time to look at this scenario and has a plan. Of course the policymakers have the final word as to military operations. Absent a direct attack against NATO, it seems unlikely that the US military would be called upon to retaliate with a proportional response against Russian forces. Rather, diplomatic actions will dominate as the United States consults its allies to determine what the next step would be. It may be escalatory; it is difficult to say what happens next because there is no contemporary precedent for a nation using tactical nuclear weapons. The US national security community has not openly discussed and debated what happens after the first nuclear bomb is used. We’ve had our minds elsewhere for the past twenty years.

Russia and China are both considering the practical application of these weapons in the context of regional conflicts. As a result, we need to accept the possibility of tactical nuclear weapons use. It is arguably folly to discuss military conflict with China and Russia that remains at the conventional level. We need to address the conventional-nuclear transition and establish processes to coordinate between geographic combatant commands and US Strategic Command, as well as with our allies. Within the government, the national security community is hampered by the excessive security classifications over nuclear weapons issues. While the DoD nuclear community can outline scenarios and develop plans, the majority of the policymakers and military staffs don’t engage in open discussions on what US nuclear capabilities are or how we might respond to limited nuclear warfare. This is not “thinking about the unthinkable” to steal a line from Herman Kahn. I am not promoting the idea of engaging in limited nuclear warfare with Russia as a result of its actions in Ukraine. However, we need to better understand the possibility of adversary use of such weapons and to discard the faulty assumptions that currently exist to prepare for and protect against that future. Tactical nuclear weapons are a threat to the United States and its alliance relationships. We need to deal with it.

Al Mauroni is the director of the US Air Force Center for Strategic Deterrence Studies and author of the book, Countering Weapons of Mass Destruction: Assessing the U.S. Government’s Policy.

The views expressed are those of the author and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense, or any organization the author is affiliated with including the Air University and US Air Force.

Image: Russian 2S7M Malka nuclear-capable artillery systems during training exercise in 2022 (credit: via Wikimedia Commons)