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Every few days, Russia’s rhetoric around the potential use of a nuclear weapon in Ukraine seems to shift back and forth. One day, Russian military leaders are discussing plans for the use of a tactical nuclear weapon; another day, the Kremlin is stating explicitly that a nuclear war should never be fought, and that using such weapons would have no political or military value.
While there are numerous rungs on the metaphorical escalation ladder before the nuclear question would come into play, there are at least three distinct scenarios for Russia’s use of a nuclear weapon, each of which differs in rationale and likely consequences.
Scenario 1: A Signaling Device
Rationale: Russia could test nuclear weapons as a warning to Ukraine and its supporters, demonstrating both its resolve and capability. Actions speak louder than words, so testing a nuclear weapon could drive home Russian President Vladimir Putin’s past statements that this “special military operation” in Ukraine is becoming an existential conflict for the Russian state.
The last Russian nuclear test occurred under the Soviet Union on October 24, 1990; and, apart from North Korea, no state has conducted a nuclear test since 1998. Russia could conduct a nuclear demonstration in its northern regions, international waters, or an uninhabited part of Ukraine. Each of these options would, respectively, be more brazen in the extent to which they would depart from decades-old norms surrounding testing. Russia would likely take care to ensure that the test causes no casualties and yields minimal radioactive fallout.
Likely effects: A nuclear demonstration would not tilt the balance in favor of either side. The efficacy of even Russia’s most advanced nuclear weapons is likely already known to relevant Western governments, and a test likely would not incentivize Ukraine to capitulate because Kyiv already feels that the conflict is existential. Russia’s recent aerial bombing campaigns have shown that, if anything, a nuclear demonstration is likely to harden Kyiv’s resolve and engender more sympathy and support from the West.
The humanitarian and environmental effects are also likely to be minimal, as the test site would be chosen with those impacts in mind. One unwanted side effect could concern Russia’s relations with China. China has tried to tow a careful line in maintaining the strong personal relationship between President Xi Jinping and Putin without kindling outright hostility from the West. China has thus far been sympathetic to Russia’s broader strategic goals in Ukraine, but a Russian nuclear test could put Beijing in a tough position. Xi recently stated China’s opposition to any country using or threatening to use nuclear weapons.
Scenario 2: A Battlefield Weapon
Rationale: Russia could use nuclear weapons against Ukrainian military or energy infrastructure targets in an attempt to weaken the country’s will and damage its military capacity. Tactical nuclear weapons have a smaller payload and more precise targeting, which makes them conducive to battlefield use. Russia has about two thousand tactical nuclear weapons that it could deploy by plane, missile, or ship. It would most likely use the short-range Iskander-M missile system. These weapons have yields of 1–50 kilotons, the largest of which would have a blast radius about half a kilometer wider than the bomb the U.S. military dropped on Hiroshima, Japan, at the end of World War II.
In one hypothetical, Russia could target Ukrainian forces in Luhansk near the Troitske-Svatove-Kreminna line to prevent Russian forces from having to retreat, like they did in Kherson. A nuclear attack could weaken those Ukrainian forces and create an uninhabitable no-man’s-land that would make Ukraine think twice about advancing before or during the winter.
Likely effects: Russia’s use of a tactical nuclear weapon against military targets on the battlefield would be unlikely to halt the Ukrainian counteroffensive. Even if a battlefield nuclear weapon made a land advance more challenging, Ukraine would likely continue its focus on aerial attacks and air defense in ways that have been successful in recent weeks. Moreover, using nuclear weapons on the battlefield would be less effective in shutting down Ukrainian electricity and energy infrastructure than conventional bombing because their higher yield and lower accuracy makes them ill-suited for those targets.
The environmental effects of tactical nuclear weapons use are difficult to calculate and would depend on warhead yield, detonation height, weather, and local geography. Russia would be cautious not to detonate weapons too close to its own soldiers or occupied territory.
China would almost certainly be forced to publicly denounce such weapons use by Russia, and the resulting distancing would have repercussions for future China-Russia cooperation more broadly.
The West likely would not respond to tactical nuclear use by sending troops into Ukraine, but the United States and its allies would likely ramp up the number of conventional weapons they send to Ukraine. Western states would also be more willing to provide non-military humanitarian assistance in response to the fallout and radiation, which could also affect neighboring countries.
Scenario 3: A Weapon of Terror
Rationale: Russia’s most escalatory option is also the least likely—using a strategic nuclear weapon against Ukrainian civilian targets or Ukraine’s neighboring international partners. Such an attack would be hundreds of times more powerful than one that used tactical weapons. Russia’s aim would be to weaken Western resolve, and it would likely target military installations or infrastructure relevant to the Ukrainian war effort, such as arms supply lines in Poland or weapon storage facilities in the Baltics. Bombing a major Western city such as Paris or Los Angeles, by comparison, would only elicit a stronger Western reaction. This is also the scenario where a Western nuclear response is most likely.
While the Ukraine conflict is not an existential threat to Russia, Putin could perceive it as a threat to himself. He likely fears that losing the war would mean losing power or his life. As the likelihood of that prospect increases, Putin could view nuclear weapons as a last resort for self-preservation, no matter the external costs. Russia recently raised alarms in Western capitals by alleging that Ukraine was planning to use an improvised nuclear device often referred to as a “dirty bomb.” Experts say most of the damage from such a device would be from its explosion, and that it would pose far less of a radiation threat than a traditional nuclear weapon. Ukraine and its allies dismissed the claim as false and potentially deceptive propaganda intended to give Russia a pretext to escalate the war with nuclear weapons.
Likely effects: Using a nuclear weapon against civilian or non-Ukrainian targets would certainly generate a retaliatory response from Western states. The United States would be unlikely to default to nuclear weapons given its confidence in the demonstration of resolve that would result from a swift, sophisticated conventional response, which would also be tactically effective. Eastern European members of the North Atlantic Treaty Organization (NATO), who could fear becoming Russia’s next target, would be particularly interested in ensuring that the alliance mobilizes a response that sends a strong signal to Russia that nuclear use will never help it achieve expansionist objectives.
President Joe Biden has staked out the U.S. position on the issue, noting, “Any use of nuclear weapons in this conflict on any scale would be completely unacceptable to us as well as the rest of the world and would entail severe consequences.” This vagueness is intentional and consistent with a long-standing U.S. policy of “strategic ambiguity” aimed at giving U.S. policymakers flexibility in deciding how to respond to nuclear events.
More direct Western involvement would dramatically change the intensity of the conflict. Absent U.S. casualties from a Russian nuclear attack outside of Russia or Ukraine, U.S. involvement will likely remain indirect through increased arms sales and nonmilitary support. The United States could be more likely to use conventional weapons directly against Russia, although it would take care to signal that it aims to defend Ukraine and the West rather than conquer Moscow. Any Western troop deployment would not cross the border into Russia, and even the use of advanced cruise missiles, drones, and ground operations would be limited to Russian targets in Ukraine. Non-kinetic operations such as cyberattacks would likely continue, although little would be known about those until well after the war is over.