‘Battlefield nukes’ in Ukraine? A low but complex threat.

In her experience running war games for the U.S. military, Stacie Pettyjohn found that whenever scenarios involved nuclear weapons, participants tended to be flummoxed. 

“Normally folks playing the U.S. side are at a loss as to what to do,” she says. It was not uncommon for teams to unnecessarily escalate hostilities – and stumble into the nightmare of nuclear war. “It’s one of those things that’s terrifying,” she said. 

Time and again, though, the prospect of “mutual assured destruction” served as a powerful enough deterrent during the real world of the Cold War, and in subsequent decades fears of a nuclear armageddon began, rightly or not, to decline considerably. 

Today, however, speculation surrounding Russian President Vladimir Putin’s potential use of so-called low-yield, or tactical nuclear weapons in his war on Ukraine is sounding atomic alarms for a new generation. 

The prospect of Mr. Putin dipping into his arsenal of battlefield nuclear arms raises the specter of disastrous escalation should NATO retaliate in kind – or the possibility of ushering in a new era in which aggressors can get away with their limited use if it doesn’t.

Mr. Putin could also gain concessions through the mere threat to go nuclear, implicit though it has been. “His standard operating procedure is to inject nuclear weapons into nonnuclear crises – hypothetically to induce restraint in his adversaries and raise anxiety, which might make it easier for him to accomplish his objectives,” says Adam Mount, director of the Defense Posture Project at the Federation of American Scientists.

Particularly given the Biden administration’s efforts to de-escalate when it comes to nuclear rhetoric, analysts stress that the use of such weapons in Ukraine is highly unlikely; keeping it that way will be the challenge in the days and months to come.

“The risk of Russia using a nuclear weapon in Ukraine is very low, and the public concern over nuclear use has far outstripped the nuclear risk,” Dr. Mount says.

And that is in keeping with Mr. Putin’s “escalate to de-escalate” strategy. “In some ways,” Dr. Mount adds, “it’s the threat that’s meant to do more work than the weapon itself.”

Davy Crockett and other “small” atomic weapons

The United States was cavalier about its own development of “small” atomic weapons shortly after the dawn of the nuclear era in the 1950s, when it produced an array of battlefield nuclear land mines, artillery, and warheads. 

“It was this idea that ‘radiation’s not good, but we’ll figure it out later,’” says Nikolai Sokov, senior fellow at the Vienna Center for Disarmament and Non-Proliferation in Austria.

Among the most infamous in this arsenal was the Davy Crockett Tactical Nuclear Weapon, which weighed about 75 pounds and was designed to be launched by a rocket or a gun, giving it a range of less than 3 miles.

Owing in large part to its “finned watermelon” shape, it was, U.S. military developers learned in Nevada tests, highly inaccurate. Still, the Pentagon built some 2,100 of them before phasing it out of service in 1967. 

Should U.S. revive focus on “low-yield” nuclear weapons?

By 1991, the U.S. had eliminated thousands of these weapons from its nuclear arsenal. Today, the U.S. has some 230 tactical nukes, with roughly 100 deployed to Europe, according to a Congressional Research Service report released in February. Russia has an estimated 1,000 to 2,000 tactical warheads.

Former President Donald Trump’s administration argued that America’s reserves of these weapons should once again grow. Gen. John Hyten, then head of U.S. Strategic Command (StratCom), argued in their favor. “If an adversary employs low-yield nuclear weapons on the battlefield, the only option that we have should not just be go big,” he said.

“Low yield” is a bit misleading, however, as many of these weapons are between 8 and 10 kilotons. The bomb that the U.S. used in Hiroshima was roughly 15 kilotons – and killed 80,000 people initially, with thousands more dying later of radiation exposure. “There’s this idea that, ‘Oh, it’s under 10 [kilotons] so it’s not that bad.’ That is definitely a misnomer,” says Shannon Bugos, senior policy analyst at the Arms Control Association.

While some of these tactical nuclear weapons received renewed congressional funding under the Trump administration, the Biden administration has not appeared to be interested in moving forward with the program, analysts say.

Avoiding an escalation in rhetoric

The administration has certainly declined to amp up any rhetoric around tactical nuclear weapons deployment. In response to news reports last month that Mr. Putin put his nuclear forces on “high alert,” Pentagon officials downplayed the tough talk.

When asked about Russia’s potential use of tactical nuclear weapons, a senior defense official, speaking on condition of anonymity in a March 31 background briefing, said that there were “no indications at this time that they’re preparing to use those kinds of weapons.” Pentagon officials have emphasized this point repeatedly. 

Indeed, ultimately reports of the “high alert” status of Russian nuclear forces more accurately translated to a “special regime of combat duty,” suggesting Mr. Putin was staffing up facilities rather than preparing to launch weapons, says Ms. Bugos. 

“There was this breathless nuclear-war-is-right-around-the-corner talk that we saw after Putin’s statement,” she notes. In the arms control community, however, “We were like, ‘Yes, it’s concerning,’ but things we were monitoring, like Russia rolling out it’s nuclear-armed ICBMs [intercontinental ballistic missiles] – we weren’t seeing that. Those are the signs that to us would be a lot stronger marker of Putin contemplating nuclear use.” 

This clarity on the part of the Biden administration is a vital U.S. de-escalation strategy, adds Dr. Pettyjohn, now director of the Defense Program at the Center for a New American Security. “One thing you see time and again in war games is how easy it is to misunderstand an opponent.”

When signals go wrong

A nuclear near-catastrophe in the midst of a 1983 NATO exercise known as Able Archer offers a case in point. Its purpose was to simulate nuclear escalation as allied defense forces moved from DEFCON 5 to DEFCON 1, which signals the outbreak of nuclear war.  

The problem was that exercise was highly realistic and included new codes and the participation of heads of government, leading some Soviet officials to believe it was a ruse for an actual first strike. 

In response, the USSR began loading nuclear warheads onto its combat planes. The threat abated when the U.S. military advised against responding in kind or putting NATO forces on a similar state of high alert, and the exercise ended. 

Perhaps with this bit of military history in mind, Defense Secretary Lloyd Austin recently ordered the postponement of a scheduled Minuteman III ICBM test. 

“Part of our test planning includes over-communicating what we’re doing,” Vice Adm. Jon Hill, director of the Missile Defense Agency, said in a March 28 Pentagon briefing. “If I’m told to back off or delay or change [weapons tests], we will do that,” he said. “We have to be concerned about political-military concerns all the time.” 

Response “would have to be asymmetric”

That’s in large part because, though Mr. Putin does not appear to be preparing to use it, Russia’s nuclear arsenal is, like America’s, well-maintained and ready to go. 

The final steps rather simply involve moving the warheads from their storage facilities to “mate” them with their “nuclear delivery vehicles,” as the process is known in Pentagon parlance. This does, however, offer a small window for de-escalation.

“It’s reassuring in the sense that you can actually see warheads being moved, and then you have a couple of hours to contact the other side,” says Dr. Sokov.

Still, U.S. military planners are working around the clock to offer responses for a worst-case scenario, such as “if Putin uses a nuke – or nukes plural,” says retired Col. Robert Killebrew, a former instructor in strategy at the U.S. Army War College who wrote a book about the relationship between nuclear and nonnuclear warfare. 

Mr. Killebrew estimates that NATO forces “wouldn’t respond in kind” in Ukraine since it would grievously harm civilians and cause the U.S. to lose the support “of about half of NATO right away.” 

As a result, “The response would have to be asymmetric,” he says. “And it would have to be devastating.”

The Pentagon is likely “looking for pressure points outside the immediate theater, like the Russian Navy,” Mr. Killebrew adds. “We might sink their Black Sea fleet. We have ships in the Black Sea also. The Russian Navy against the U.S. would last about 30 minutes.” 

Envisioning a new treaty

Averting any such scenarios is the challenge for the short term. In the long run, arms control experts express hope that these nuclear scares for a new generation could inspire the world to begin limiting such weapons of mass destruction, particularly since low-yield nuclear weapons haven’t been addressed in past nonproliferation treaties. 

While the U.S. tended to support slashing their stockpiles, the Russians long relied on low-yield nukes to compensate for their own lack of conventional weapons relative to the U.S., says Dr. Mount of the Federation of American Scientists.

Russia would like the U.S. to reduce its stockpile of conventional arms in exchange, which so far the U.S. has been unwilling to do.  

These mutual interests – and the war in Ukraine – could ultimately serve as impetuses to bring the superpowers back to the negotiating table. 

Simply getting discussions underway would improve international stability, says Dr. Sokov, particularly with New START nuclear nonproliferation set to expire in 2026. 

He worked on negotiations for the START 1 treaty, which went into effect in 1994. In those days, the political atmosphere was “very favorable” and it still took them four years to hammer out the details, even as Russian and U.S. negotiators “worked in complete harmony, really.”

This is not likely to be the case in the years to come, but it would be “a very good development,” he says, “if we could just see these negotiations begin.”

Editor’s note: This article has been updated to correct the spelling of Nikolai Sokov’s name.