As Russia’s war in Ukraine grinds on, the remnant of the old Soviet Union threatens nuclear war and violates a landmark arms-control treaty. The Biden administration dismisses this as saber-rattling and the peace groups that screamed for disarmament during the Cold War are silent. Has the West learned to stop worrying and, if not love the bomb, at least ignore it?

As the fates of Hiroshima and Nagasaki fade from memory, atomic weapons have become the stuff of films and fiction, with younger Americans shrugging off “Duck and Cover” as nostalgia and Cold War paranoia. If these modern people are persuaded only by movies, they would do well to remember the computer’s lesson from the 1983 film “War Games” — that the only winning move in a nuclear war is “not to play.”

Tell that to the Kremlin. “The defeat of a nuclear power in a conventional war,” a former Russian president, Dmitry Medvedev, posted on Telegram when warning against backing a Ukrainian victory, “may trigger a nuclear war.” Last week, a member of the Russian Duma, Andrey Gurulyov, said that until Americans “get hit with a nuke on their skulls, they won’t come to their senses.”

After Russia tested its Satan II ICBM last April, a former lieutenant general in the Red Army, Evgeny Buzhinskiy, celebrated. “If 7.5 megatons will be delivered to the territory of our so-called partner,” he said of America, “then objects like the City of New York … would be gone.”

Another Russian MP, Yuri Shvytkin, painted a similarly apocalyptic scenario. “The warheads in the missile are indeed capable of hitting enemy targets,” he said. “So you understand, there would be virtually no New York left — there would be virtually no England left — from a single missile.”

The record shows, of course, that President Trump was not above this kind of saber rattling himself. He did this most famously in his “Little Rocket Man” speech at the United Nations, when he tried to force Kim Jong-un into talks by threatening to obliterate North Korea. Russia, though, actually has the means of delivering the nuclear weapons they are threatening to use.

Plus, the Russian president, Vladmir Putin, has threatened nuclear war again and again, saying it’s “not a bluff.” He maintains the world’s largest arsenal and is now refusing to allow inspections to ensure they’re not expanding it. NATO noted “with concern that Russia has failed to comply with legally binding obligations under the New START treaty.”

Words on paper, of course, are no obstacle to Moscow. Mr. Putin violated the Budapest Memorandum — signed in 1994 along with the U.K. and America — promising to respect Ukraine’s borders, annexing Crimea in 2014 and launching the full-scale invasion one year ago. Yet a conventional wisdom of denial has taken shape in the West.

It reckons that Russia won’t use nuclear weapons because we say so. In the event cities are reduced to radioactive rubble, they may pan the strategy of Imperial Japan’s wartime prime minister, Hideki Tojo, who — in diary entries released in 2008 — planned to ignore the rain of atomics.

On “Meet the Press,” President Biden’s national security adviser, Jake Sullivan, pledged “decisive” action in the event of a nuclear strike. “If Russia crosses this line,” he said, “there will be catastrophic consequences for Russia. The United States will respond decisively.” On “60 Minutes,” the secretary of state, Antony Blinken, warned that “the consequences would be horrific.”  

Despite this doomsday rhetoric, the peace movement seems absent from public debate. I wrote in the Sun on August 2 of last year that the Doomsday Clock — a touchstone of the “no nukes” lobby — had remained unmoved despite Russian belligerence. Last month, the Bulletin of the Atomic Scientists ticked the clock’s hands the closest they’ve been to midnight, symbolizing Armageddon.

Even this is only “largely, but not exclusively” about Ukraine, adding “climate change, biological events, and the misuse of other disruptive technologies,” as if nuclear weapons no longer present the singular road to human extinction. The world may have forgotten its power, but the atomic genie is just the push of a button away from escaping — and the only way to win a nuclear war remains not to play.