Weapons of mass destruction could be the 'red line' Putin crosses to draw NATO into his war

While NATO has resisted military intervention against Russia, the potential use of chemical and even small tactical nuclear weapons in Ukraine could be the red line that triggers a response from the Western alliance, experts say.

NATO summit will likely discuss 'red lines' for military action in Ukraine

NATO Secretary General Jens Stoltenberg has said Russia's use of chemical weapons would have far-reaching consequences. (Oliver Matthys/The Associated Press)

While NATO has resisted military intervention against Russia, the potential use of chemical and even small tactical nuclear weapons in Ukraine could be the red line that triggers a response from the Western alliance, experts say.

Yet setting such red lines come with challenges, and risk and fears of expanding the war into a global conflict.

NATO has made it clear that any deliberate attack by Russia on an alliance member would prompt, as NATO Secretary General Jens Stoltenberg has stated, a "decisive response from the whole alliance."

However, there "are many different scenarios that are less clear that could draw NATO into a larger war with Russia," said Roland Paris, director of the Graduate School of Public and International Affairs at the University of Ottawa. "And that is an extraordinary risk."

Military response could widen the war

Although the idea of using weapons of mass destruction shocks the conscience, a military response to such attacks threatens to widen the war, Paris said.

"The potential for this to become a world war would be significant," he said.

Observers fear a desperate Russian President Vladimir Putin might use weapons of mass destruction in Ukraine. (Mikhail Klimentyev/Sputnik/Kremlin Pool Photo/The Associated Press)

How NATO may respond to the use of chemical, biological or even tactical nuclear weapons within Ukraine, a non-NATO country, is something that will likely be a focus of Thursday's NATO summit in Brussels.

"I think that what you're probably going to see at these meetings this week is kind of finding out whose trip lines are where so that NATO is ready to respond," said Elizabeth Shackelford, a former diplomat with the U.S. State Department and a senior fellow at Chicago Council on Global Affairs.

"It's my guess that it's going to be pretty contentious over who wants to do something more extreme and who doesn't."

Vague threats

So far, leaders in NATO have made vague threats that Russia would pay if it were to launch weapons of mass destruction, without defining what specific action might be taken.

U.S. President Joe Biden has said that Russia would pay a "severe price" if it launched chemical weapons. And on Wednesday, Stoltenberg told a news conference that if Russia used chemical weapons, it would "totally change the nature of the conflict" and have "far-reaching consequences."

But he also said he would not "speculate about any military response from the NATO side except for saying very clearly that NATO's main responsibility is to make sure that we defend and protect all allies."

Some observers have raised concerns that, with Russia's invasion of Ukraine faltering, a desperate Vladimir Putin might resort to some form of weapons of mass destruction in the country. 

"I suspect that Putin understands the risks of using weapons of mass destruction in Ukraine," Paris said. "Up until a month ago, I would have thought that would never be a risk that he would take in the European context. But he's made decisions that are so reckless that there's no predicting his next steps."

Earlier this month, Polish President Andrzej Duda told BBC that the use of weapons of mass destruction "would be a game changer," and that NATO "will have to sit at the table and they will really have to think seriously what to do because then it starts to be dangerous."

As for chemical weapons, Shackelford said that may not trigger an automatic military response from NATO, but would depend on how or where they were deployed.

'Depend on what they did'

"I think it would be horrific. It would be alarming. But I think that it would depend on what they did. For example if it was a military target versus a civilian target," she said. 

"Are they trying to kind of poison an area that people can use supplies there, versus are they actually spraying chemical weapons in a highly densely populated area with people fleeing the war," she said. "I think those would merit a different reaction from NATO."

WATCH | Russia must stop 'nuclear sabre rattling,' Stoltenberg says: 

Russia must stop 'nuclear sabre rattling,' says NATO chief

2 years ago
Duration 1:33
NATO Secretary General Jens Stoltenberg addressed fears of chemical or nuclear attacks during Russia's war against Ukraine, saying: 'A nuclear war cannot be won and should never be fought.'

Putin has previously implied he would launch nuclear weapons against any country interfering in Russia's invasion of Ukraine and ordered his forces on high alert. Earlier this week, his chief spokesman Dmitry Peskov told CNN that Russia might resort to nuclear weapons in the face of an "existential threat" to the country.

Although such comments have raised significant worry, the more immediate concern, say some observers, is the potential use of tactical nuclear weapons.

Russia is believed to have around 2,000 tactical nuclear weapons, with only a small fraction of the kiloton power of strategic nuclear weapons. They can still cause enormous damage but have significantly less blast capacity than those used in Hiroshima and Nagasaki.

A Ukrainian soldier stands in the ruins after Russian shelling of a shopping center, in Kyiv, Ukraine, March 21, 2022. At least eight people were killed in the attack. (Efrem Lukatsky/The Associated Press)

Putin might fire a weapon at an uninhabited area instead of at troops, Ulrich Kühn, a nuclear expert at the University of Hamburg and the Carnegie Endowment for International Peace, told the New York Times. 

And that, says Shackelford, would merit a qualitatively different response by NATO. Any use of nuclear weapons risks normalizing the idea that this could be a nuclear war, she said.

"I can't see Russia using any form of nuclear weapon and that not being something that the West can sit on the sidelines for, because at that stage, what we're trying to do is to not invite an escalation. And that would be a massive escalation."

Problems with red lines

Still, setting red lines may also provoke Russia, some experts suggest. 

"We should hope that NATO won't set a red line. This would be an invitation for further escalation by Russia and further efforts to damage NATO's credibility," said retired Gen. Wesley K. Clark, former NATO Supreme Allied Commander, Europe.

WATCH | NATO response unclear if Putin launches chemical, nuclear weapons:

NATO response unclear if Putin launches chemical, nuclear weapons

2 years ago
Duration 2:04
As experts raise concerns over the potential for Russian President Vladimir Putin to deploy chemical and nuclear weapons in his invasion of Ukraine, it's still not clear how NATO would respond to such an escalation.

Michael Kimmage, who served on Secretary of State John Kerry's policy planning staff, where he held the Russia/Ukraine portfolio, said setting red lines in this case is also complicated by the fact that Ukraine is not a NATO member. 

"There are questions of precedent and where things would apply. If the Russians use chemical weapons in Ukraine, that's a problem for NATO. If the Chinese use chemical weapons somewhere else, is that a problem for NATO?"

Kimmage said it would be better not to declare red lines and be boxed into a corner.

Instead, if Russia used chemical, biological or nuclear weapons, it would be better to marshal as big of an international coalition as possible, one that includes China, and start to exert a kind of pressure on Russia that it hasn't yet seen, he said.

WATCH | Russia more likely to use chemical weapons, analyst says:

Chemical, biological weapons more likely to be used in Ukraine than nuclear, expert says

2 years ago
Duration 9:35
Though Russian President Vladimir Putin is more likely to order the use of chemical or biological weapons in the invasion of Ukraine, nuclear weapons are still possible, said Andrew Weber, former U.S. assistant secretary of defence for nuclear, chemical & biological defence programs.

"But I don't know if that all has to be spelled out beforehand," he said.

Harry Nedelcu, director of policy at Rasmussen Global, an international political consultancy firm, echoed that any potential NATO response to such actions should be deliberately left unclear.

"That is actually very potent because you need a bit of that veil of uncertainty to actually increase your power to deter," he said.

"It's actually a good idea to not even spell out exactly what it is."


Mark Gollom

Senior Reporter

Mark Gollom is a Toronto-based reporter with CBC News. He covers Canadian and U.S. politics and current affairs.