India too has an obligation to prevent Russia from going nuclear

There is no clear end in sight to the war in Ukraine. Although Ukraine has made recent military gains, Putin has doubled down, by annexing parts of Ukraine and portraying Russia’s invasion as part of a civilisational war with the West. The Russian leadership has also hinted that nuclear weapons could come into play. As well as the rhetoric, there are real concerns that the changing nature of nuclear weapons may destabilise the traditional deterrence equation – creating many more possible scenarios than nuclear strategists and game theorists imagined during the Cold War. Moscow’s nuke option For years now Russia and other nuclear-armed states have invested in “tactical” nuclear weapons that are designed to be deployed in a war-fighting situation on the battlefield, rather than on long-range missiles aimed at the capitals of other nuclear states. Putin has repeatedly invoked Russia’s nuclear weapons in his recent speeches, though he said in late October it would not make sense for Russia to use a nuclear weapon in Ukraine. He noted that Russia has a clear doctrine setting out the conditions under which nuclear weapons could be used. But this is not wholly reassuring.The Russian doctrine includes the option to use nuclear weapons if the state faces an existential threat. Defeat in Ukraine might be embarrassing for Russia, but would not be an existential threat.However, Putin may think defeat would be an existential risk for his presidency. And the recent annexation of Ukrainian land could allow him to argue that Ukrainians recapturing their own land were “attacking the Russian homeland”.In game theory terms, Putin might calculate it would be worth using a nuclear weapon in Ukraine on the basis that so-called tactical nukes could have a strategic effect, and act as a game-changer in a conflict where the Russian army otherwise seems to be losing.If so, he would be gambling not only that Ukraine would back down, but that the US administration would see any further escalation as too dangerous once nuclear weapons were involved. But that would be a big gamble. Russia has already miscalculated the strength of US and European support for Ukraine earlier in this war. For Nato countries, nuclear use by Russia would increase the stakes in Ukraine: If Russia won by using a nuclear weapon, other nuclear-armed states would conclude that the nuclear age had ushered in a new era of nuclear impunity, where they could do what they liked in regional conflicts and territorial disputes because no one would dare fight them. In particular, the US worries about the lessons that China would draw. Many more countries would seek to obtain these weapons for themselves. The West’s second-strike choices The US has said it has communicated to Russia that there would be “catastrophic consequences” for breaching the nuclear taboo. Probably even in private the US has been deliberately ambiguous about what those consequences would be – and specifically, whether they could involve nuclear weapons use. In Europe, Macron recently indicated to the media that France – one of the three nuclear powers in Nato – would not use its nuclear weapons if Russia used a nuclear weapon in Ukraine. Nato countries may want to avoid a nuclear response, and they have many non-nuclear options.Retired senior US general, David Petraeus, has suggested that if Russia used a nuclear weapon, the US and Nato could destroy Russia’s troops in Ukraine and sink its Black Sea fleet.He also noted that if Ukraine’s Nato neighbours suffered devastating fallout they might seek to trigger Nato’s collective defence provisions.The US and its allies will also be considering a variety of alternative options from cyberattacks disabling Russian infrastructure to massive sanctions on third parties doing business with Russia. Fallout for the world But even if the US opted to avoid immediate nuclear retaliation, any option looks likely to bring it into a much more direct confrontation with Russia. In game theory terms, it would not be a one-shot game like mutual nuclear strikes; it would be a repeated game that could take on many levels and drag in new players. Such a confrontation could easily get out of control, and could take on nuclear dimensions at any point. For the rest of the world, nuclear weapons use in Ukraine would unleash a cascade of risks from the toxic effects on ecology and climate, to the knock-on effects on refugee flows, to disruptions to food and supply chains, financial risk premiums and global economy. But in a multipolar world, it is not only about the US and Russia. China may have a significant role in restraining nuclear threats. India too could play an important role by acting as a voice for restraint in its bilateral contacts with Russia, and in its upcoming G20 presidency. As a nuclear-armed state it has an interest in ensuring such weapons are used only to deter, and not to destroy. The writer is a director at European Leadership Network