President Joe Biden traveled to New York on Thursday for an otherwise ordinary Democratic fundraiser.

Except that Biden’s remarks at the private event were a big deal.

The president issued a dire warning about the threat of nuclear war. “We have not faced the prospect of Armageddon since Kennedy and the Cuban missile crisis,” he said. It was a signal of the severity of the moment the world is in amid Russia’s war with Ukraine.

As Biden explained, “We’ve got a guy” — Russian President Vladimir Putin — “I know fairly well. He’s not joking when he talks about potential use of tactical nuclear weapons.” Putin said several times last month he would use “all weapon systems available” to Russia if its “territorial integrity” was violated, and he said he wasn’t bluffing.

The Bulletin of the Atomic Scientists warned even before Russia’s invasion that the globe sits “at doom’s doorstep.” The setting of its Doomsday Clock sits at 100 seconds to midnight, the most ominous position of the dial since its creation in 1947.

The nuclear experts I spoke with agree that Biden’s comments were, without a doubt, attention-grabbing. There’s decidedly less consensus on whether they were helpful or alarmist.

“It’s sort of the crazy stuff we used to talk about during the 1970s and ’80s,” Hans Kristensen, a researcher with the Federation of American Scientists, told me. “It’s pretty insane that three decades after the end of the Cold War, we still have to entertain these kind of thoughts.”

While worries about nuclear war have been present since Moscow invaded Ukraine nearly eight months ago, what’s different now is just how tangible the threat is compared to any point since the end of the Cold War. Between Putin’s menacing comments, Russia’s illegal annexation of Ukrainian territory even as Ukraine advances, and ever more US support for Ukraine, the danger is concrete enough that Biden is unnerved.

What Biden is telling us

Putin is causing the threat right now. His decision to illegally annex four territories in eastern Ukraine in September raises questions as to how Putin, in his desperation, will treat these contested regions. Fears persist about whether he’d be willing to use a small nuclear weapon over those territories or elsewhere.

But Biden’s words, too, have power.

Nuclear experts agree that Biden’s statement was accurate, but there is not consensus as to whether Biden’s remarks were the right thing to have said aloud.

Biden was “deeply reassuring” by expressing the severity of what’s happening, says James Acton, a nuclear expert at the Carnegie Endowment for International Peace. “I think this gives you an idea about where his mind is at. He literally is the president of a country with hundreds of millions of people living in it, during an actual honest-to-god nuclear crisis,” he said.

For Kristensen, however, “presidential statements become mileposts that contribute to the escalation of a crisis.” (White House officials clarified that nothing had changed to prompt Biden’s comment.)

Nevertheless, Biden’s claims may play into Putin’s power. “Putin is looking at this and he’s saying, ‘Well, wow, the US president, he thinks I’m actually going to do this, that means I have a card to play,’” Kristensen told me.

He also emphasized that the Cuban missile crisis was a true hair-trigger scenario. Today US intelligence agencies report that, despite Putin’s rhetoric, it doesn’t appear that Russia has mobilized the parts of its nuclear arsenal that would be used for a smaller strike on the Ukrainian battlefield. So while it’s appropriate to highlight the ongoing danger, Kristensen said that we’re not yet in a direct Russian-US nuclear standoff. By comparing it to the emergency situation of the Cuban missile crisis, where both US and Soviet nuclear arms were loaded, Biden “has gone a bit over the top here.”

The small cabal of nuclear watchers has been warning of the growing nuclear peril even before the current Russia-Ukraine war, among them Lynn Rusten, who served as a senior arms control official in the State Department during the Obama administration and now works at the Nuclear Threat Initiative.

Rusten thinks that Biden’s warning was warranted. “The Biden administration has been extremely restrained and constrained and how it has handled Russia’s saber-rattling since the beginning of this crisis,” she told me. “He said what we know to be true. And it just makes it clear that it’s important for leaders to find a way out of this.”

The scene of the comments shouldn’t be lost on us. Biden was speaking at the home of James Murdoch, who in addition to being the son of media magnate and Republican booster Rupert is also a major investor in the influential military contractor Rebellion Defense. Murdoch the younger is also a former board member of the TV network Fox, where Tucker Carlson and others have urged appeasement with Russia and limiting US involvement in Ukraine.

Diplomacy is the only way out

Beyond the alarming assessment, Biden said something rather remarkable: He noted the urgency of seeing Russia’s war of aggression from Putin’s perspective.

“We are trying to figure out: What is Putin’s off-ramp? Where does he find a way out?” Biden said. “Where does he find himself where he does not only lose face but significant power?”

Inherent in Biden’s comment is that engaging with the Russian government is crucial to avoiding a worst-case scenario.

“We’ve gotten to the point where we’re starting to treat diplomacy like it’s a reward for good behavior, instead of a tool that you use with your adversaries and enemies,” Rusten told me. “That’s pretty risky. Because I think if you don’t have these channels of communication, I think it’s a lot easier to dehumanize” the adversary than to engage diplomatically with them.

The incredibly challenging task of arms control is crucial for global stability. Biden ought to remind Americans that his predecessor, former President Donald Trump, recklessly withdrew from the three-decade-old Intermediate-Range Nuclear Forces (INF) treaty. That accord set hard-won limits on Russian and US missiles.

Still, it’s worth noting that Russia is still some steps away from readying its unconventional arms.

The Kremlin keeps its weapons separately from the systems that would launch them into oblivion, according to Pavel Podvig, an independent researcher who studies Russian nuclear forces. Still, the risk is serious. To Podvig, what’s missing from the US conversation is restraint: too many instant-experts are saying that if Russia uses a nuclear weapon in Ukraine, the US needs to be tough by responding to Russia perhaps with a small nuclear weapon. “My take is that you just don’t go there, because that’s not worth it. There would have to be a response, of course, but it would have to be along the lines of the total isolation” of Russia.

White House spokesperson Karine Jean-Pierre said today, “We have not seen any reason to adjust our own nuclear posture, nor do we have indications they are preparing to use them.” And the US has reportedly back-channeled to Russia about the hazardous weight of Putin’s threats. Dialogue like that is key.

As Rusten put it, “We may all have a lot of divergence, but arguably we still have a mutual interest in not blowing each other and the world up with nuclear weapons.”