Ukraine's thrust into Russia up-ends assumptions on nuclear war  

Washington D.C, United States

When Ukrainian forces stormed across the border with Russia in August, they set two historic milestones. It was the first time since World War Two that a foreign army had thrust into Russia.  

It was also the first time that a non-nuclear country had carried out a major incursion into the territory of a nuclear superpower, a country that has the world’s biggest nuclear arsenal. It was an operation that threw doubt over what military strategists call nuclear deterrence theory.  

That theory dates back to 1949, when the Soviet Union detonated its first atomic bomb in 1949, four years after the first and so far only use of nuclear weapons—the American bombs that destroyed the Japanese cities of Hiroshima and Nagasaki and killed more than 200,000 people, mostly civilians.  

The Soviet test of its bomb prompted countries from Asia, Europe, and the Middle East to pursue nuclear weapons of their own. Over the decades, the nuclear club grew to nine—the United States, Russia, Britain, France, China, India, Pakistan, North Korea and Israel.  

While there have been limited military conflicts between nuclear-armed countries—India has had borders skirmishes with Pakistan and China—none have used nuclear weapons. That restraint has roots in a Cold War concept developed by the US and then Soviet Union—MAD, short for Mutually Assured Destruction.  

The awesome power of nuclear arsenals led to the assumption that no country fielding only conventional weapons would strike into the territory of a nuclear power.  

Ukraine put that belief to the test on August 6, when more than 10,000 Ukrainian troops backed by tanks and armoured vehicles stormed into Russia’s Kursk region and seized roughly 1,250 square kilometres of Russian territory. Ukrainian President Volodymyr Zelensky said his troops had taken control of 92 settlements in the first two weeks of the assault.  

Since Russia launched an unprovoked all-out war on Ukraine in February 2022, President Vladimir Putin has issued veiled threats to use tactical nuclear weapons in the conflict. In June, Russia and its neighbour and close ally Belarus carried out exercises to simulate the deployment of such weapons.  

They are designed for battlefield use, unlike strategic weapons developed for vast distances, such as from Russia to the United States or one of its European allies. Though they are not as powerful as strategic weapons, the battlefield versions match the destructive power of the Hiroshima and Nagasaki bombs.  

According to published Russian military doctrine, a threat to the country’s sovereignty and territorial integrity would justify the use of nuclear weapons. Apparently, Ukrainian control of a sizeable chunk of the Kursk region does not qualify.  

Oddly, Kremlin propaganda has refrained from reminding citizens of the outside role Kursk played in what Russians call the Great Patriotic War against Nazi Germany.  

The battle of Kursk, in July and August 1943, was the largest tank battle in history, involving 6,000 tanks, close to two million soldiers, and 4,000 aircraft. It ended with a German defeat and was a turning point, a few months after the famous Battle of Stalingrad, in the war the Nazis lost in 1945.  

No tactical nuclear weapon has been used since the beginning of the nuclear age, partly because of the risk of triggering a full-sale nuclear war, partly because of deadly radiation that would cause long-term health damage to survivors, partly because of radioactive fallout that would contaminate air, soil, water, and the food supply, experts say.  

Last month’s Ukrainian thrust into Kursk had several military objectives—force Russia to redeploy units from grinding battles in the east of the country, seize territory and take prisoners that might be used for bargaining leverage in possible future peace negotiations, and show the Russian population that the war Putin started could hurt them inside their own country.  

But the operation also carried a message for the administration of US President Joe Biden—you have been wrong in hesitating and delaying the supply of sophisticated weapons for fear of escalating the conflict by crossing a Russian "red line." In a speech on August 19, Zelensky called American fears of Russian red lines "a naïve, illusory concept."  

American military and economic aid to Ukraine has been a contentious subject, with former US President Donald Trump and many of his Republican backers opposed and Democrats firmly in favour.  

Wrangling in Congress led to a four-month pause in supplies and a halt on a $61 billion aid package providing for artillery, air defence systems and missiles.  

None of them have sufficient range to strike deep into Russia and hit the air bases and supply depots Russia has been using for a devastating attack on Ukraine’s infrastructure. Zelensky’s calls for longer-range missiles have been rebuffed, again, for fears that their supply would draw the US more deeply into the conflict.  

Russia’s nuclear warnings have come against the background of what some experts are calling a new nuclear arms race at a time of major arms control setbacks. Last year, Russia suspended its participation in the 2010 Treaty on Measures for the Reduction and Limitation of Strategic Nuclear Arms, better known as New START.  

That is bound to expire in February 2026, by which time there will be no major treaty limits on the number of strategic weapons the United States and Russia deploy. China, whose nuclear arsenal is growing rapidly, halted nuclear arms control talks with the United States in July in protest of US arms sales to Taiwan.  

While China lags far behind the US and Russia, its nuclear arsenal is now the world’s third-largest. It is estimated at around 500 warheads, a number expected to double before the end of the decade.  

Relations between China and Russia have grown so close that a statement was released at the end of a summit in Washington to mark the 75th anniversary of the North Atlantic Treaty Organization (NATO). The statement termed the government of Beijing a decisive enabler of Russia's war on Ukraine.  

Which helps explain Biden’s caution on dealing with the largest conflict in Europe since World War II. The present constellation of forces makes telling the difference between a serious red line and a bluff, a tricky business.