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The possibility of nuclear war in Ukraine still looms

Editor’s note: This post is the first in a three-part series entitled “Is it legal for the U.S. to attack Russia if Russia nukes Ukraine?” by Dakota S. Rudesill, Associate Professor at the Moritz College of Law at The Ohio State University. Image: Kirill_makarov –

Part I: The possibility of nuclear war in Ukraine still looms

Last fall, senior U.S. officials made clear that “catastrophic consequences” would follow if Russian strongman Vladimir Putin employed one or more nuclear weapons against Ukraine, where Russia has been waging the largest war in Europe since World War II. These U.S. warnings went farther than repeated public warnings by U.S. President Joseph R. Biden.

Based on public record, we can gather that the Biden administration’s concerns about Russian employment of one, or a small number, of its thousands of relatively low-yield tactical nuclear weapons (which I have written about here) were driven by multiple factors. One was Kremlin desperation to win a failing, terribly costly, and incompetently executed war. Another was the intensification of Russian nuclear saber rattling. A third was intelligence indicating that Russian generals had discussed the circumstances under which Russia would break the nuclear taboo that has existed for more than 75 years.  

U.S. officials in public maintained calculated ambiguity, but some were quoted in ways that fueled speculation about a punitive U.S. strike if Russia crossed the nuclear threshold. Public discussion and, reportedly, internal U.S. government deliberations focused on a massive potential U.S. conventional (non-nuclear) attack on Russian forces operating in or near Ukraine, to, for example, sink the Black Sea Fleet headquartered in Russian-occupied Crimea. 

The Biden administration’s warnings, together with others from Beijing and elsewhere, appear to have had a role in Russia’s lack of resort to nuclear weapons last fall. World leaders and experts have rightly warned that the Ukraine War and its potential for escalation have created the greatest risk of nuclear war since the 1983 Able Archer war scare or the 1962 Cuban Missile Crisis. It is therefore good news indeed that the risk of Russian nuclear use appears lower today. It is especially encouraging that Russian President Vladimir Putin appears to be able to listen to signals from other world actors. Russia’s strongman has been extremely isolated in recent years due to the pandemic, personal security worries during the war, and surrounding himself with sycophants, producing a disconnection from reality and critical feedback that were key factors in Putin’s obvious failures to predict and therefore to plan for Ukrainian and international reaction to his February 2022 attack. Putin is obviously ready to spill massive amounts of Ukrainian and Russian blood to restore Russian imperial power over tens of millions of people who reject it, yet does not seem completely locked inside the bellicose, resentful, paranoid worldview that Fiona Hill and other Kremlin watchers have warned could lead Putin to order an atomic atrocity against Ukraine. 

Even so, it is entirely foreseeable that nuclear use could be back on the table for Putin as the war grinds on. A year and a half in, there is no end of the war clearly in sight. Circumstances could change quickly. Rising domestic pressures on Putin to end the war, another internal move against the Kremlin akin to the Wagner Group’s June 2023 revolt, more battlefield setbacks, or deterioration of Putin’s mental state could prompt renewed concern about Russian resort to nuclear weapons, one of Russia’s few real claims to power parity with the United States. As the U.S. Intelligence Community warned in its 2023 annual threat assessment, “the risk for escalation remains significant,” and Russia is likely to respond to massive losses to its conventional forces with increased reliance on cyber, space, and nuclear capabilities. The next time worries about Russian nuclear use grow, warnings from Washington, Beijing, and elsewhere may fall on deaf Kremlin ears.

In short, we could again be faced with the question of how the United States should respond to a Russian nuclear strike on Ukraine, and particularly whether that U.S. response should include use of force. The primary U.S. goal for such a punitive attack would be to raise the costs of Russia’s atomic atrocity so high that Russia would refrain from further nuclear use, thereby restoring nuclear deterrence. The U.S. could also seek to damage Russian forces so deeply that the Kremlin could no longer continue the war.

The massive risk, of course, is that a U.S. attack would have the opposite effect: generation of Russian conventional retaliation against U.S. forces or our NATO allies. That, of course, could lead to a general Russia/NATO conventional war, one that would be costly for both sides but an already battered Russian military would be unlikely to win. Desperate Russian resort to battlefield use of tactical nuclear weapons could ensue, followed by NATO retaliation in kind to restore deterrence. Use of strategic nuclear weapons against the homelands of the nuclear-armed American, British, French, or Russian combatants—in other words, global thermonuclear war—would loom as potentially civilization-ending further rungs up the escalatory ladder. 

Overstating nuclear risk is an obvious hazard, but so too is ignoring it. It is imperative to think carefully now about possibilities and potential consequences. A key reality here is that no NATO/Russia war nor any nuclear war has ever been fought, and therefore nobody really knows whether escalation could be controlled. How much any of this might shape Putin’s reaction to the United States sinking the Black Sea Fleet or devastating its ground forces in occupied Ukraine is a vital matter for assessment by experts on Russia, nuclear weapons, and international security. In our republic, it is ultimately a first-order geopolitical and government decision-making question, too, for the president, Congress, and the American people.

What I have just outlined in Part I is the factual context for two posts that will follow on an important legal question: the legality under U.S. law of a presidential order to the military to punish Russia for nuking Ukraine.

Remarkably, this question got essentially no attention last fall from the general public or in public legal discourse. It deserves focused engagement now, before nuclear tensions rise again.

The main contention of this three-part blog series—forthcoming in expanded form as a contribution to the Ohio State Law Journal’s symposium on the Ukraine War and the Law—is that unless there are clear indications that Russia is seriously preparing or has initiated an armed attack on the United States, U.S. forces, or NATO allies, the case under U.S. law for the legality of the U.S. striking Russia simply because Russia uses a nuclear weapon against Ukraine is not strong. After such a further outrage in a war already rife with Russian war crimes, as awful and illegal as it would be, the president as a question of U.S. law must either wait for clear indications of a truly imminent or initiated follow-on Russian attack on the United States in order to invoke the Commander in Chief’s national self-defense constitutional authority, or else secure a force authorization from Congress. The optional nature of such a punitive U.S. attack on Russia, and the colossal risk of escalation if incurred unilaterally by the president without any regard for Congress’ constitutional role, would make such a U.S. strike inconsistent with the Constitution’s vision of shared power in national security. Thankfully, alternatives exist, ones that are legal and may shape Russian decisions.

Part II of this series, coming soon, explains why—despite sympathies on my part for Ukraine that could not be stronger—it is my firm conclusion that a presidential order to strike the Kremlin’s forces after a Russian atomic atrocity, without indication of a specific follow-on attack to the West, would push presidential war authority beyond its outer edge.  Although President Biden’s executive branch lawyers may disagree, Part II will make the strong case that, under the Constitution’s vision of shared congressional and presidential war power, none of the four bases for use of force abroad pursuant to the president’s authority under Article II of the Constitution is operative.

Part III of this series sets out a range of alternatives to a U.S. kinetic attack. These overt and covert courses of action could have considerable deterrent power on Russia if threatened, and substantial punitive power if employed. I conclude this three-part series by warning any readers in Russia against assuming that Russia could avoid paying a massive price for nuking Ukraine—or that force would be off of President Biden’s menu of options. I am confident in the analysis I will offer, but I acknowledge—and caution—that the president and his executive branch lawyers may not agree. In short, if the Kremlin is worried about what President Biden might do, it should stay worried.

Dakota S. Rudesill is an Associate Professor of Law at the Moritz College of Law, and Senior Faculty Fellow at the Mershon Center for International Security Studies, at The Ohio State University. You can find his scholarship here at SSRN and follow him on Twitter.

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