Putin placed Moscow’s nuclear forces on high alert shortly after his invasion of Ukraine began on Feb. 24, and he warned that “no one should have any doubts that a direct attack on our country will lead to the destruction and horrible consequences for any potential aggressor.” But U.S. officials did not noticed any changes to their footprint or movements at the time. In April, Russian foreign minister Sergey Lavrov warned the West not to underestimate the elevated risks of nuclear conflict over Ukraine. Putin supporters on Russian state TV in recent weeks have talked openly about a nuclear war with the U.S. and Europe.
U.S. intelligence officials say they have seen no signs that Russian President Vladimir Putin is poised to employ so-called battlefield nukes.
A Russian nuclear doctrine evolved in what Western officials consider disturbing ways. In a 1993 document, Russia said it would use nuclear weapons only when the existence of the country was threatened. But in versions published since 2000, Russia have envisioned the first use of nuclear weapons in response to a conventional threat in a regional war. And military experts say Russia’s smallest warheads have many times the explosive power of the bombs dropped on Hiroshima and Nagasaki.
The doctrine also allows for the use of nuclear weapons “in response to large-scale aggression using conventional weapons in situations critical to the national security of the Russian Federation.” Experts have described that strategy as “escalate to de-escalate,” and they say it means that Russia is willing to make limited use of nuclear weapons to win what would otherwise be a conventional war.
On paper, U.S. nuclear doctrine is similar, but in practical terms, experts do not believe an American president would ever use nuclear weapons in a regional conventional war, and the U.S. has not, through Korea, Vietnam, Afghanistan and Iraq. Officials say the main purpose of the U.S. nuclear arsenal is to deter or respond to a nuclear attack by an adversary. Still, the U.S. has not ruled out using nuclear weapons in response to biological or chemical attacks, and in some limited circumstances, conventional attacks. It still maintains around 100 nuclear weapons in NATO countries, put there originally to stop Russian tanks from seizing Western Europe.
Officials are struggling to understand exactly what could prompt Putin to use a nuclear weapon. To cement gains made on the battlefield? To reverse losses? To stave off a rout?
“It’s not clear where that red line is. If Ukrainian forces were to enter Russian territory, would that be sufficient? I don’t know,” said Chris Chivvis, who served from April 2018 to April 2021 as the U.S. national intelligence officer for Europe.
It’s a troubling question with no palatable answer: What would President Joe Biden do if Russia used nuclear weapons in the Ukraine war? When the Obama administration conducted a war game simulating Russian use of nuclear weapons in the Baltics, there were fundamental disagreements about how to react.
“We don’t see … practical evidence at this point of Russian planning for the deployment or even potential use of tactical nuclear weapons,” CIA Director William Burns said last month. But, he added, “given the kind of saber-rattling that … we’ve heard from the Russian leadership, we can’t take lightly those possibilities.”
It’s fair to say that the American response “would depend wildly on how the Russians used” a nuclear weapon, as one U.S. official regularly briefed on U.S. government deliberations put it.
Putin presumably expects his threats will induce NATO to abandon Ukraine. However, if he believes he is facing defeat or a costly stalemate—or has a chance of success through sharp escalation—there is some non-zero (perhaps a worryingly high 1 or 2 percent) risk he will carry out his threats. Even a small risk is deeply dangerous, and he should recognize the risk of starting a nuclear war, so deterring him is the most desirable outcome. Accordingly, NATO should say clearly that any nuclear attack by Russia would meet with a response, potentially including nuclear weapons.
According to Stoltenberg, it is necessary to continue to monitor Russia’s behavior, including nuclear exercises and the rhetoric used by the head of the Kremlin, Vladimir Putin. The Secretary General noted that nuclear blackmail is dangerous and increases tensions, but Russia has not yet changed its position on this matter. “We remind Russia that they have agreed that a nuclear war will not be a winning one, so it cannot be started. Russia’s use of nuclear weapons will absolutely change this conflict,” Stoltenberg said.
The menu of NATO options must be stark: Stay the course, up the sanctions and keep arming the Ukrainians, while building an international coalition against Russia that completely isolates the country
