Adnan R. Khan is a writer and analyst based in Istanbul.
Russian President Vladimir Putin’s escalatory actions in Ukraine are raising some unsettling questions over how far he is willing to go to win his war. So far, the lines crossed have included the indiscriminate shelling of civilian neighbourhoods, preventing civilians from using humanitarian corridors to escape the fighting, using civilians as human shields and using autonomous killer drones.
The United States has warned that the Russian military may now be preparing to use chemical or biological weapons in a false flag attack it can blame on the Ukrainians. And on Feb. 28, Mr. Putin publicly ordered his top generals to put Russia’s nuclear arsenal on its highest state of alert.
Crossing the Rubicon into nuclear war may have sounded inconceivable a month ago, but today it ranks as an outside possibility. That’s frightening enough, but the specifics of what experts believe Mr. Putin may be planning suggest even more troubling ripple effects well into the future.
Most of those experts agree that the potential for Russia dropping a large-yield “strategic” warhead in Ukraine, something that would almost certainly trigger a nuclear response by the U.S., remains close to zero. The more realistic possibility, they say, is a tactical weapon dropped on isolated Ukrainian forces, or even detonated over the Black Sea, as a way to shock the Ukrainians into surrendering.
The potential use of these weapons has raised some thorny questions that have remained unanswered ever since the 1960s. When does a low-yield nuclear strike cross the threshold into an all-out nuclear war? Is a tactical nuclear strike on an advancing army that causes little collateral damage justified?
The conundrum lies in trying to identify at which point a tactical nuke, which can vary in explosive yield from as little as a few tons of TNT to several thousand, ceases to function as a deterrent to war – and instead becomes a means of waging it.
“Tactical nukes were designed for battlefield use,” Hans Kristensen, the director of the Nuclear Information Project at the Federation of American Scientists, told me recently. “You didn’t want to pop a nuke that creates a lot of radioactive fallout over the entire area where not only adversaries have to operate, but also perhaps your own troops. It was that kind of consideration that led to these variable yield selections in them.”
Pakistan, for instance, has relied on tactical nukes to balance out the overwhelming advantage its arch-enemy India has in conventional forces. The strategic thinking is straightforward: If in a conventional war India overwhelms Pakistan, the Pakistanis believe they can use tactical nukes for strikes on the Indian army without triggering nuclear Armageddon.
It’s a twisted logic, but it may also be what Mr. Putin is considering. The use of a tactical nuke in Ukraine, all the experts I spoke to unanimously agreed, should not trigger a reciprocal response from the U.S. or its nuclear-armed allies. Indeed, it should not even trigger a conventional military response, which could then escalate into an all-out nuclear war.
The prudent response to Mr. Putin, if he goes down the nuclear path, is for the world to further isolate Russia politically and economically. If the device is detonated in an unpopulated area as a way to send a message, it could also be treated as a violation of the 1963 Limited Test Ban Treaty rather than as nuclear aggression, some experts have suggested.
Given the stakes, the odds of the war in Ukraine leading to nuclear Armageddon remain exceedingly low. Even the Bulletin of Atomic Scientists have kept their Doomsday Clock at 100 seconds to midnight, the same level of threat it has been at since 2020.
Herbert Lin, a member of the Bulletin’s Science and Security Board, wrote recently that he believes the danger of a nuclear war is currently at about 5 per cent to 10 per cent of the threat during the Cuban missile crisis. “Still,” he added, “that I am measuring the current situation against the event that was the closest the world has ever come to global nuclear war is a stark reminder of the stakes involved.”
The more pressing danger is how a limited use of a tactical nuclear weapon by the Russians would change the strategic thinking of other nuclear-armed nations. China, India and Pakistan all possess tactical nukes. They are no doubt curious to see how the world will react if Russia opens up that Pandora’s box; that reaction will shape the future use of these weapons.
This is the line Mr. Putin will cross if he goes with the nuclear option. In doing so, he will no doubt push the Doomsday Clock many more precious seconds forward.
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