Behind the scenes, we’ve told the Russians precisely what we would do if they crossed the nuclear threshold in their conflict with Ukraine. Yet to avoid ratcheting up the war of words with Moscow we won’t be relaying those details in public. That’s the combination proffered by Joe Biden’s National Security Advisor. But in his several appearances on Sunday morning’s television news shows, Jake Sullivan also ventured an assurance that America and its allies would “respond decisively” and that the consequences for Russia would be “catastrophic.”

The White House might have avoided that form of words if it had wanted us all to believe it was ruling out a response in kind should Russia go nuclear. To roll out a tired metaphor, an American nuclear response does not appear to be entirely off the table. But as the Carnegie Endowment’s James Acton points out, should it come to that point it is not clear what nuclear card Russia would be dealing. Might it be an intimidating “demonstration” strike above the Black Sea rather than the detonation of one of Russia’s smaller nuclear warheads on the Ukrainian battlefield? Or something else?

Nuclear threats from Russia’s leaders are neither novel nor rare. Painstaking analysis from Berlin’s SWP suggests literally dozens of these can be identified in Russia’s words and actions from the end of January to the middle of August this year. But the “what’s next” question is becoming more pressing for political-military reasons. After the stage-managed extraction of pro-Kremlin votes from eastern Ukrainian territory occupied by Russia’s forces, the expected annexation announcement could see Putin insisting that any further advances by Kyiv will be treated as attacks on Russia itself. And that provocative insistence would have obvious nuclear connotations. Washington does not appear to be picking up the sort of intelligence it would expect to see if a nuclear move from Moscow was impending. But public reporting also suggests that the US has intensified its hunt for signs that Russia’s forces are being readied for some sort of nuclear use.

The scale and nature of that use would have a bearing on the response. Following Sullivan’s intervention, Poland’s Foreign Minister has suggested that if Russia was to explode one of its smaller nuclear weapons on Ukrainian territory, the US and NATO reaction should be “devastating”, but in a conventional way. Long-time arms control advocate Jim Cirincione has come up with an almost entirely non-nuclear menu of responses to what he sees as Russia’s four main nuclear options. But he is pushing his logic to breaking point by suggesting that even in the improbable event of a Russian nuclear attack on a NATO member country, a non-nuclear response is “more likely” than a nuclear one.

Highly accurate missiles paired with destructive but non-nuclear warheads could certainly cause massive damage to Russian armed forces and other targets. And they would still bring the US and NATO directly into the fight, raising the question of what Moscow would do next. But there is something uniquely catastrophic about the use of nuclear weapons, reflected in the idea that the world has been observing a nuclear taboo since the bombing of Nagasaki and Hiroshima. The apparent singularity of the nuclear threshold is also revealed in our fears that as soon as the first nuclear weapon is used, there may be no obvious way of stopping the escalation.

Yet the threshold factor is not as homogenous or straightforward as we sometimes think. Russia has nuclear options of varying degrees of awfulness, just as some of America’s responses would be much more catastrophic than others. However much they may currently be talking to each other, walking the escalatory walk would be a voyage into the unknown. It’s hard to imagine that in their private conversations, Moscow has made Washington’s life easier by fixing on a single nuclear option and describing it in granular detail. By the same token, it is also unlikely that their discussions have traversed the full range of America’s responses to each one of Russia’s potential choices, let alone how Russia will act after that.

Moscow may nonetheless believe that with one wrong move it could easily trigger a truly devastating reaction from America and its NATO allies. But there is still likely to be some uncertainty over when and in what circumstances that decisive and catastrophic response would kick in. In the meantime, Putin’s nuclear rhetoric is unlikely to disappear or become more reasonable. But what he decides to do with Russia’s nuclear arsenal matters more than what he chooses to say about it.

Encouraging China and India to exert whatever calming influence they may have on Russia’s leadership is a good idea. Other Asia-Pacific countries which still have functioning relationships with Moscow should do the same. Those efforts are much more likely to occur behind closed doors than in the full glare of public diplomacy. But our desire to know why Russia has made its next choices is outweighed by our collective need to live in a world where nuclear use is averted.

–Published in partnership with the Nautilus Institute.

Disclaimer: The opinions articulated above represent the views of the author(s) and do not necessarily reflect the position of the Asia Pacific Leadership Network or any of its members. APLN’s website is a source of authoritative research and analysis and serves as a platform for debate and discussion among our senior network members, experts, and practitioners, as well as the next generation of policymakers, analysts, and advocates. Comments and responses can be emailed to apln@apln.network.

Image: Russian Foreign Minister Sergey V. Lavrov briefs journalists at UN Headquarters on September 24, 2022, during the general debate. UN Photo/Jaclyn Licht.