What is a ‘tactical’ nuke, and would Putin use one?

Photo illustration: Mae Decena. Sources: Naeblys/FPG/Getty Images

Some experts say there’s really no such thing. All experts agree: This is uncharted territory.

Just in case you were wondering, Vladimir Putin has nuclear weapons.

Almost from the moment he launched his war on Ukraine, Russia’s president has repeatedly made not-so-subtle references to Russia’s nuclear arsenal and warned Western countries of his willingness to use it. He did so yet again on Wednesday at a speech in St. Petersburg. “If anyone decides to meddle in ongoing events and create unacceptable strategic threats for Russia,” he warned, “they must know our response will be lightning-quick. We have all the instruments for this, ones nobody else can boast of. And we will use them, if we have to.”

The speech came a few days after Foreign Minister Sergei Lavrov said in a televised interview that while Russia was seeking to avoid nuclear war, “the danger is serious, real. And we must not underestimate it.”

Putin’s nuclear threats have been somewhat effective — the threat of nuclear escalation is a big reason why NATO countries have avoided taking certain retaliatory steps, such as imposing a no-fly zone over Ukraine, which would risk direct combat with the Russian military — but only up to a point. Western countries are now training Ukrainian troops on their soil and providing Ukraine with aircraft and increasingly heavy weaponry, measures that were seen by many as dangerously escalatory just a few weeks ago.

There are also fears that Putin could use one of his “instruments” on the battlefield in Ukraine if the war continues to go poorly for the Russian military. In a speech earlier this month, CIA Director William Burns warned that “given the potential desperation of President Putin and the Russian leadership, given the setbacks that they’ve faced so far militarily, none of us can take lightly the threat posed by a potential resort to tactical nuclear weapons or low-yield nuclear weapons.” Ukrainian President Volodymyr Zelenskyy agreed that Russia might use a nuke on the battlefield in a CNN interview.

Aside from the Kremlin’s vague threats, there’s no evidence Russia is planning to use a nuclear weapon, but the mere possibility is sobering. This would mark a turning point not just in the war in Ukraine, but in world history. A nuclear weapon has not been used in war since 1945, and never in a world where other countries could retaliate with nuclear weapons of their own. And experts who spoke with Grid say that euphemistic terms like “tactical nukes” and “low-yield nukes” should not obscure the damage such a weapon would cause or the larger risks it would create.

As Shannon Bugos, a senior policy analyst at the Arms Control Association, told Grid, “A nuclear weapon is a nuclear weapon. Once you’ve introduced a nuclear weapon onto the battlefield, that’s the endgame. There’s no coming back.”

“Tactical” nukes: A distinction without a difference?

What exactly is a “tactical nuclear weapon”? For starters, some military experts don’t think the distinction is useful at all. As then-Secretary of Defense James Mattis put it in congressional testimony in 2018, “I don’t think there is any such thing as a ‘tactical nuclear weapon.’ Any nuclear weapon used any time is a strategic game-changer.”

The term “tactical” is often used to imply that the bomb is smaller or less powerful, but this is misleading at best. Some “tactical” warheads in the U.S. arsenal have yields of around 100 kilotons. That’s smaller than some of the larger bombs available today, but still massive: The bomb used on Hiroshima had a yield of just 15 kilotons.

Russia is thought to have some lower-yield weapons, around the 10-kiloton range. If that doesn’t sound like much, consider that the port explosion that destroyed much of downtown Beirut in 2020 was less than 1 kiloton.

In the current conversation, “tactical” nuclear weapons are distinguished from “strategic” ones, but the difference has less to do with the bombs themselves than how they would be used. Strategic warheads typically refer to those which the U.S. and Russia would fire at each other’s territory in the event of an all-out nuclear war. The target is the enemy’s society, not just its military. The bombs dropped on Hiroshima and Nagasaki were the textbook example. A “tactical” weapon, on the other hand, would be used for some specific gain in the theater of war. “A tactical nuclear weapon is basically a weapon that you would use to gain advantage, get some advantage on the battlefield or on the theater of operations,” said Pavel Podvig, an expert on Russia’s nuclear forces at the U.N. Institute for Disarmament Research.

A tactical nuclear weapon could be used for a task like destroying an enemy tank column or a large target like an airfield. Nuclear depth charges designed to destroy submarines or the nuclear-armed missile defense system that the Soviets deployed around Moscow would be other examples of “tactical nukes.” They are generally thought of as having shorter range. A nuclear missile fired from a ground-based artillery system, like the Russian Iskander launchers that have been deployed around Ukraine, would generally be considered tactical.

Jeffrey Lewis, a professor at Middlebury College’s Center for Nonproliferation Studies who agrees there’s “no such thing” as a tactical nuclear weapon, said the distinction was in large part created by U.S.-Russian arms control agreements like the 2009 New START treaty: “Those agreements only cover stuff that goes on [intercontinental ballistic missiles] and submarines, and heavy bombers. And so we call those ‘strategic.’ Sometimes you’ll hear people say ‘non-strategic,’ instead of tactical, which basically means everything that’s not covered by the strategic arms agreements.”

According to some estimates, Russia may have between 1,000 and 2,000 of these non-strategic weapons.

Would Russia use one?

“If you look specifically at the current war, the fact of the matter is that there are no plausible tactical missions for nuclear weapons,” said Podvig. “There are no massive tank columns moving toward Luhansk or aircraft carriers to destroy. There is no way that Russia could gain advantage on the battlefield [with a nuclear weapon.]” The only plausible mission for nukes, he said, would be a Hiroshima-style “strategic” attack meant to force Ukraine to surrender.

As for what would lead Russia to resort to such an attack, some analysts believe, based on the statements by Russian analysts and officials, that the country has an “escalate to de-escalate” strategy, in which it would use nuclear weapons to force surrender, compensating for disadvantages on the battlefield or to avoid an imminent defeat. It should be pointed out that this is not the official Russian doctrine, which states that first use of nuclear weapons is permissible only “when the very existence of the state is under threat.” Kremlin spokesperson Dmitry Peskov referred specifically to this doctrine in an interview with PBS in late March, saying, “We can use and we will actually use nuclear weapons to eliminate the threat for the existence of our country.”

Podvig pointed out that “there is wiggle room there to interpret that broadly. It’s not like someone will be arguing this in court.”

Ultimately, one man will decide what constitutes a threat to the state. Putin’s narrative on the war in Ukraine, after all, is that Russia is defending itself from NATO aggression, and he has often framed the conflict in existential terms for Russia. This doesn’t mean he will use his nuclear weapons, but it’s not hard to imagine how he would make the case that doing so was necessary for the state’s survival. There’s a reason the White House quickly walked back President Joe Biden’s off-the-cuff remark last month that Putin “cannot remain in power.”

What happens next?

If Russia used a nuclear weapon, no matter how small, “tactical” or “strategic,” and no matter what the target, it would shatter a taboo that has been in place for almost 80 years, and it’s far from clear what would happen next. Ukraine’s Western allies would be under pressure to respond in kind, but using a nuke in response to a nuke risks a chain of escalation that could end in Armageddon.

Slate journalist Fred Kaplan has reported that the Obama administration once considered a scenario like this in a war game simulating a Russian invasion of the Baltic nations, in which Russia used a low-yield nuclear weapon to turn the tide after a battlefield setback. While the generals in the war game favored a nuclear response, Colin Kahl, then Biden’s national security adviser, now undersecretary of defense, argued for diplomatic and economic pressure to isolate Russia.

Both options, and a wide range of responses in between, are likely to be heard if worse comes to worst. The world would be in uncharted territory. As Lewis pointed out, “we’ve all fought the same number of nuclear wars. Zero.” And written doctrines, past precedent and war games are of very limited use in guessing how one would play out. “It’s not rational to use a nuclear weapon,” said Lewis. “It’s not rational to retaliate with a nuclear weapon. None of this is rational.”

Thanks to Lillian Barkley for copy editing this article.

Joshua Keating

What is a ‘tactical’ nuke, and would Putin use one?