Russia’s war of aggression against Ukraine has thrown into sharp relief the role that nuclear weapons may come to play, once again, in relations between the major powers. From a western perspective, Russia’s nuclear threats before and during the war mark an inflection point after some three decades of steady nuclear weapons marginalisation on the part of the US, the UK and France. The gravity of the emerging strategic environment is all the more evident when Russia’s threats, and its vast nuclear arsenal, are considered alongside China’s burgeoning nuclear capability, which could see Beijing deploy 1,000 warheads on various long-range and theatre-range delivery systems by 2030. President Xi’s growing bellicosity over Taiwan, and the ‘no limits’ friendship between Moscow and Beijing, provide further focus for western minds as the world moves inexorably towards nuclear tri-polarity over the coming decade. North Korea’s continued progress towards operationalising its nuclear capability is an additional cause for concern, of course.

Nuclear weapons and the war in Ukraine

Before Russia’s invasion, Moscow brandished its nuclear capability to deter NATO countries from becoming directly involved on the side of Kyiv. Key to this was Russian nuclear signalling, notably bringing forward an annual exercise for strategic forces immediately prior to the invasion. At the same time, direct military involvement was ruled out by the US and others in NATO, to reduce the chances of escalation between the alliance and Russia. NATO also sought to deter horizontal escalation – specifically, Russian action against member countries — which primarily involved moving conventional forces to eastern member countries alongside Ukraine and Russia. The fact that NATO is a nuclear alliance is clearly part of its deterrence posture, although there was no obvious flagging of this by the alliance, and the three nuclear members of NATO have all been very critical of Russia for its nuclear signalling.

Since the invasion, Russia has continued to flex its nuclear wherewithal to deter direct western involvement, although this has not prevented NATO’s increasing military assistance to the Ukrainian armed forces. This assistance has enabled Ukraine to repel and reverse Russian military gains and has been provided despite statements from Moscow that it could lead to escalation. Since 24 February, Russia has raised its nuclear alert status, conducted ICBM (intercontinental ballistic missile) tests, and various senior officials, including President Putin, have issued multiple statements both playing up, and playing down, the nuclear risks and threats in the context of the war. Since Russia began to fail militarily, the risk of nuclear escalation by Moscow has been framed primarily against the country’s conventional military performance, and the potential inability of Putin to credibly declare some sort of victory. Here, the concern is that Moscow could use nuclear threats, and potentially even the use of low-yield nuclear weapons against targets in Ukraine, as a way to compel Kyiv and its western backers to accept a ceasefire, negotiations and an outcome to the war on Putin’s terms.

For most of the war, the risk of Russian nuclear escalation has tended to be focused on anything that might threaten to reverse Moscow’s gains from 2014, specifically, the annexation of Crimea. But since early September, anxiety about the nuclear issue has heated up because of Ukraine’s successful counter-offensive in the east and the south. With the annexation of Luhansk, Donetsk, Zaporizhia and Kherson, the risk of nuclear use has further intensified. This has been accompanied by growing talk from senior Russian officials about the escalation potential as Russian conventional forces are challenged. Russian statements have included reference to ‘all means’ being available to defend Russian territory, as defined by Moscow, and Putin’s reference to nuclear use in Hiroshima as a precedent in a recent call with French President Macron. Russian accusations that Ukraine possesses a ‘dirty bomb’ have been interpreted by many as potentially preparing the ground for nuclear use by Moscow. For its part, the US has sent a ‘clear message’ to Russia about the ‘catastrophic consequences’ of nuclear use in Ukraine.

There has been some dialling down of the nuclear rhetoric from Moscow in the past couple of weeks, despite the withdrawal of Russian forces from Kherson. This may be due to increased communication between Russian and American officials, the reported US encouragement of Ukraine to be open to negotiating with Russia when the time is right, and/or China convincing Moscow to reduce the nuclear heat. Nevertheless, a heightened nuclear risk remains in the Ukraine context.

Framing the nuclear future

When, or if, the war in Ukraine results in a re-freezing of the Russia-Ukraine conflict, and assuming the war does not escalate in a nuclear sense, what issues might shape the nuclear question going forward?

Russian nuclear signalling has shown that nuclear deterrence works. NATO has been deterred from getting involved militarily in a direct sense to support Ukraine. Looking ahead, different actors may react differently, depending on where they sit. For newer nuclear weapon states, such as North Korea, India and Pakistan, and nuclear aspirants like Iran, the lesson is likely to be that the possession of nuclear weapons can help to protect vital interests. Furthermore, nuclear possession could enable flexibility in how the conventional military lever is used in pursuit of national interests in conflict scenarios. For example, if Iran acquired a nuclear weapons capability in the medium to long term, Tehran could see this as a means to be even more assertive regionally — in how it uses proxy forces to extend external threats away from Iranian territory, and to secure its interests.

Russia had been through a long period of conventional military reconstitution and modernisation before the war. But the poor performance of its armed forces in Ukraine, and its significant combat losses, will certainly see Moscow increase its reliance, once again, on its nuclear forces, particularly its non-strategic nuclear weapons, to compensate.

The nuclear dimension to the war has fed growing concern in parts of the US defence community about the limits of America’s nuclear stockpile. There are fears about the US ability to match both existing Russian nuclear forces (1,588 deployed strategic warheads and nearly 2,000 non-strategic weapons), as well as China’s ambitious, albeit opaque, nuclear modernisation and expansion programmeRussia holds a significant advantage over the US and NATO, in terms of the types of non-strategic targets it can hold at risk with low-yield nuclear weapons. Plus, US concern extends to China’s non-strategic nuclear capabilities. Elements of the debate in the US have included senior military arguments for a new submarine-launched cruise missile, capable of delivering a low-yield nuclear warhead, although this is something the Biden administration scrapped in its recent Nuclear Posture Review. Others have argued that the US should move away from the New START agreement limiting US and Russian strategic nuclear capabilities, because it overly constrains Washington for a tri-polar nuclear future where it will simultaneously face a much more nuclear capable China, alongside Russia’s existing nuclear challenge. As General Tod Wolters, then Commander EUCOM, told Congress earlier this year: ‘Having multiple options that adversaries have to think about – exacerbates the challenge for potential adversaries acting against us.’

The evolving nuclear landscape suggests that the capabilities of NATO’s two other nuclear weapon states may also be subject to change. France already deploys a dyad of nuclear forces, including a submarine launched long-range ballistic missile capability and an air-launched cruise missile capability, the latter providing a sub-strategic option. In the UK, the Integrated Review of 2021 increased the ambiguity around the total number of warheads in the stockpile, and around the number of missiles and warheads deployed on the country’s operational ballistic missile submarines (SSBNs). Important questions now include whether the UK should contemplate becoming more ambiguous still, given the war in Ukraine. Does the UK’s ‘Moscow criterion’ — the ability to penetrate Moscow’s missile defence systems – stand up in the rapidly evolving nuclear landscape? Does the UK perceive a gap emerging, specifically in terms of British nuclear assets? Is minimum credible deterrence the right strategy going forward? These may well be issues with which the ‘refresh’ of the Integrated Review will engage.

Directly linked to above, Russia’s invasion of Ukraine has given major impetus to the nuclear mission of NATO as a whole. This includes NATO’s nuclear sharing arrangements, based on the US sharing tactical nuclear weapons with a handful of the allies, to be delivered on allied dual-capable aircraft (DCA) during wartime. For instance, Poland has announced its readiness to deploy such weapons which have, to date, not been deployed in the newer member countries that were formerly part of the Warsaw Pact. The pending expansion of NATO to include Finland and Sweden will mean another two countries deciding to come underneath the US extended nuclear umbrella.

At the June 2022 NATO summit in Madrid, the alliance’s new Strategic Concept noted that, ‘Commensurate with the threats we face, we will ensure our deterrence and defence posture remains credible, flexible, tailored and sustainable’. The new Strategic Concept also, for the first time, highlights the direct challenge posed by China to the alliance. It notes the need to address ‘the systemic challenges posed by the PRC to Euro-Atlantic security and ensure NATO’s enduring ability to guarantee the defence and security of Allies’. Given China and Russia’s ‘no limits’ friendship, and Beijing’s growing conventional and nuclear military capability, how will the alliance’s future deterrence factor in the prospect of dealing with two hostile, and allied, nuclear armed states simultaneously?

Finally, there will be implications for what ‘strategic stability’ looks like in the evolving geopolitical landscape. The recent NATO 2022 Strategic Concept mentions strategic stability but does not seek to define it. Rather, it talks about how strategic stability is delivered, and how it is being eroded, but in rather general terms. It notes, ‘Strategic stability, delivered through effective deterrence and defence, arms control and disarmament, and meaningful and reciprocal political dialogue remains essential to our security’, but that ‘The erosion of the arms control, disarmament and non-proliferation architecture has negatively impacted strategic stability’. There are many important questions regarding strategic stability. Perhaps the most important is whether, for the foreseeable future, it will depend mostly on non-cooperative approaches on the part of the West – that is, more deterrence and less arms control and confidence building.