Club Briefing: Zhou Bo, Senior Fellow at the Center for International Security and Strategy (CISS) at Tsinghua University, writes in the South China Morning Post and examines the limits of Russia’s nuclear deterrence in the Russia-Ukraine conflict from both strategic and operational perspectives. It argues that, despite possessing the world’s largest nuclear arsenal and issuing repeated nuclear threats, Russia finds tactical nuclear weapons militarily inefficient and politically counterproductive in the current conflict. Their use would provoke sweeping sanctions, diplomatic isolation, and damage key partnerships. Ukraine has adopted a calibrated salami-slicing approach to avoid crossing Moscow’s red line, while NATO’s early warning systems help maintain strategic stability. The article also compares the nuclear postures of the United States, the Soviet Union, and China, highlighting China’s consistent no-first-use policy. It concludes that while nuclear weapons remain central to great-power strategic balance, their battlefield utility and deterrent credibility are increasingly being called into question.

Why haven’t Ukraine’s drone and missile attacks on Russia triggered Moscow’s use of tactical nuclear weapons, as it has threatened? When Russia is attacked time and again, one wonders what purpose it serves to have the world’s largest nuclear arsenal.

The Ukraine war is at a stalemate. Though roughly 90 per cent of the territory in East Donbas is under Russian control, its ground advances have slowed to less than 100 metres a day, according to a July 1 report by the Centre for Strategic International Studies.

Could Russia use tactical nuclear weapons as a game-changer? The answer is probably no. Historically, nuclear weapons have proven largely ineffective in conflicts between a nuclear power and a non-nuclear adversary. Despite having a nuclear arsenal, neither the United States nor the Soviet Union prevailed in their wars in Afghanistan.

The only wartime use of nuclear weapons, by the US against Japan in 1945, is no exception. The US could have secured Japan’s surrender through conventional means; the stated justification of reducing Allied casualties was partly a pretext – a core unstated objective was to signal overwhelming military strength to the rising Soviet Union.

Despite Ukraine’s drone strikes targeting Moscow, repeated attacks across Crimea and damage to major Russian refineries, Russia has so far refrained from crossing the nuclear threshold, and for good reason.

A tactical nuclear detonation in Donbas, which lies on Russia’s western border, would create radioactive fallout that risks drifting back into Russian territory. Also, given that Moscow claims the four eastern Ukrainian oblasts as Russian territory, it makes no sense for it to bomb what it considers sovereign soil.

Moreover, the battlefield itself undermines the utility of tactical nuclear weapons. Fighting is widely dispersed with few concentrated high-value military targets, rendering tactical nukes militarily inefficient and poor value for money.

A nuclear weapon, even a tactical one, remains a nuclear weapon. Any such use would immediately invite sweeping Western sanctions and blockades, force most of the Global South countries that have so far been neutral to downgrade ties with Russia, and severely damage Moscow’s key partnerships with China, India and Brazil – all of which oppose the use of nuclear weapons.

Ukraine has adopted a calibrated, salami-slicing strategy: inflicting sustained pressure on Russian forces while avoiding crossing the red line that would prompt a nuclear response. Its goal is not a reckless direct assault to retake Crimea; the peninsula’s tourism and economic foundations have already suffered lasting damage.

Ukraine President Volodymyr Zelensky’s core objective is to force Russian President Vladimir Putin to negotiate, a message clearly conveyed in his open letter to Putin last month. Besides, Nato helps maintain all early warning systems so the transatlantic military alliance can detect any signs of imminent Russian nuclear deployment.

The conflict will continue as a grinding stalemate with mass missile and drone attacks. Both sides are now able to produce these weapons at scale indefinitely. Even with an estimated Russian-Ukrainian casualty ratio of five or six to one, Russia can draw on a population of 143 million – compared with Ukraine’s 40 million – and has the option of large-scale mobilization.

The horrendous prospect of fighting to the last Ukrainian explains Kyiv’s push for a ceasefire. Yet this is precisely why Moscow has rejected such calls.

Normally, a nuclear weapon state also has a strong conventional military force. Yet Russia’s conventional military is fighting a Ukrainian army backed by whole and sustained Western support. This is not something it had envisioned at the beginning of the war. Russia’s nuclear weapons have, however, achieved one critical purpose: deterring direct Nato intervention. With the war far from over, Russia has to continue its nuclear sabre-rattling.

Its nuclear arsenal was not designed for battlefield dominance but, as with all other major nuclear powers, for the core function of strategic deterrence and preserving the balance between great powers. At the peak of the Cold War, the US and Soviet Union amassed more than 70,000 nuclear warheads in total, driven by a mutual fear of strategic disadvantage. Subsequent arms control treaties reduced the stockpiles but a strategic equilibrium remains.

There is a clear correlation between conventional military and nuclear strength. In 1982, when the Soviet Union had an overwhelming conventional military superiority over Nato, it pledged a no-first-use nuclear policy. Conversely, Nato, fearing Soviet mass tank formations on European plains, reserved the right to initiate nuclear strikes. After the Soviet collapse and a steep decline of Russian conventional capabilities, Moscow abandoned its no-first-use commitment in 1993.

China stands as the only exception. It developed nuclear weapons amid limited conventional military capacity, primarily to resist repeated nuclear coercion: US presidents Harry Truman and Dwight Eisenhower publicly threatened nuclear strikes against China during the Korean war and subsequent cross-strait crises.

For more than six decades, China has maintained an unconditional no-first-use policy and pledged never to use nuclear weapons against non-nuclear states – the most consistent posture of all the nuclear powers.

The Ukraine war is a conventional conflict shadowed by a persistent nuclear risk. It could become another “forever war” in that a lasting, comprehensive settlement remains elusive, and a formal ceasefire is nowhere in sight.

This outcome is tragic but not surprising. True global peace is a rare condition. For all of human development and material progress, a nuclear-weapon-free world will not arrive any time soon. Still, there is at least some reassurance that nuclear weapons are losing their perceived value.

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