Nearly 60 years since the Cuban missile crisis brought the world to the brink of nuclear war, Russian leader Vladimir Putin has put that cataclysmic card back on the table in his war against Ukraine.

Putin has placed his country's nuclear arsenal, the world's largest, on high alert. And he has warned the West that joining the war in Ukraine would bring “consequences such as they have never seen in their history," a not-so-veiled threat of nuclear conflict.

As a result, the specter of nuclear war has entered the national psyche in a way unseen since President John F Kennedy ordered a naval blockade of Cuba in response to the discovery of Soviet missiles there. The blockade worked, the missiles were removed, and the crisis eased.

Decades later, Putin's actions and rhetoric are being processed through a generational divide. Baby boomers are recalling Cold War memories of “duck and cover" drills at school, while many young people — whose only exposure to such risks might be from movies or video games — are wondering just what nuclear war would look like, and whether they should be worried at all.

“I'm more scared of a nuclear war today than I've ever been before. I didn't even feel this scared during the Cuban missile crisis," said Molly Landrigan, 90, who lives at a residence for seniors in Somerville. “This is the first time in my life I am glad I don't have grandkids."

Nirvana Ragland, 18, an Emerson College freshman, had a pointedly different perspective.

“I don't think we think it will actually happen," Ragland said, speaking for her circle of friends about a nuclear exchange. “Or maybe I'm not thinking about nuclear war because it would spiral my anxiety. Right now we are stressing about COVID-19 and the next assignment for school."

Still, one can find an ongoing thread on Reddit about the best fallout shelters in Somerville. Young people on TikTok are joking about a rough future for those allergic to iodine, because iodine can help block radioactivity from being absorbed into the thyroid gland.

And Instagram has handy posts about creating a nuclear bunker in the basement.

And, the threat is real enough to show up in psychologist offices. Claudette Pierre, who practices in Brookline, said she has a client “who is reporting concern about a global war — a young adult who has a family member in active duty."

Pierre is chair of the Massachusetts Psychological Association's Disaster Resource Network, and said other psychologists have told her they are counseling adolescents with concerns about nuclear war, and young men worried about being drafted and facing nuclear battle.

Perhaps Putin's rhetoric is a bluff, or perhaps it's the dangerous gambit of a man who Avril Haines,the US director of national intelligence, said has begun a war “he cannot afford to lose."

Graham Allison, a government professor at the Harvard Kennedy School who served as assistant secretary of defense under former president Bill Clinton, said that while extremely remote, it is not inconceivable that a desperate Putin would resort to nuclear weapons.

“If he's losing, or becoming tired of the situation, or if the Russian military were performing as poorly as the Western press is reporting it, he could say, 'OK, I'm going to demonstrate that I have nuclear weapons,' " and detonate a small tactical nuclear weapon off the battlefield.

With such an act, Putin would show “I'm beating my chest, I'm stamping my foot, and don't forget I'm using nuclear weapons," said Allison, a former longtime dean of the Kennedy School and a specialist in nuclear weapons.

However, Allison said, “the likelihood of the use of nuclear weapons is very, very low in Ukraine, 1 in 100."

But for some older people with memories of World War II and the Cold War, past concerns are resurfacing.

Oscar Greene, 103, said he hadn't thought about nuclear war since 1991 when the Soviet Union fell. Greene, who grew up in Williamstown, said he again fears nuclear war as he watches “Putin attempt to reconstruct the Soviet empire."

During the Cuban missile crisis in 1962, Greene was working for General Electric as an engineer and living in Medford with his wife, Ruby, and son, Oscar Jr. He remembers thinking that Nikita Khrushchev, the Soviet leader, was “crazy."

Putin reminds him of Khrushchev, Greene said, adding that perhaps Putin is “more irrational."

“For those 13 days," he said of the missile crisis, “every day that I went to work, I didn't know if I would come home to my family. It was a very scary time."

Despite the fear, Greene never spoke to his family about it. He believed that talking about the atomic bomb would upset his wife and that his son was too young for that conversation.

For some younger Americans, the threat seems vague and distant.

Kian Nhuch, 14, of Somerville, said that no one at his home or school has talked in depth about the nuclear threat. The consequences of such escalation seem too dire to be probable, he said.

“If Putin nukes us, he will have to face NATO. And I don't think even he wants to be responsible for that much global destruction," Nhuch said.

Ragland, the Emerson College student, said she talks to her friends about current affairs. They discuss where the country is headed. They examine how much of the government's budget is dedicated to war. What they don't talk about is the possibility of nuclear war.

“I think of nuclear war as something very far-fetched," Ragland said.

Her earliest memory of a connection to nuclear war is “Fallout," a video game first released in 1997. The game is set centuries after a global nuclear war, and Ragland remembers having to find bunkers in the virtual world and rationing food.

Everything else she knows about nuclear conflict comes from movies and documentaries. “Of course, this has trivialized nuclear war for my generation and maybe even romanticized it to a certain degree," Ragland said.

However, the younger generation has nightmare scenarios to prepare for that contain echoes of the “duck and cover" drills of their grandparents: “active shooter" or “lockdown" drills where they find hiding places or safe ways out of their school buildings.

The generations often also have different avenues to seek information. For Landrigan, the 90-year-old in Somerville, the news has brought more fear than previous wars because of the media's constant coverage.

“You can't get away from the news now. Back then you had to wait a week to get a little bit of news," she said, referencing newsreels that would play once a week in movie theaters.

Meanwhile, for youths such as Ragland, who has her phone on her fingertips, the road to reliable sources is difficult.

“Even with all this news around us, it takes time and effort to parse out the facts," Ragland said. “And I am always aware that we aren't being told the full story. I don't think we know the full story about Hiroshima, and I don't think we have the full story about the possibility of nuclear war."

Older generations who came of age during the “no-nukes" protests of the 1970s and '80s do not find the idea of nuclear calamity so far-fetched. When construction of the Seabrook nuclear power plant in New Hampshire began amid intense opposition in the 1970s, Landrigan remembers her brother telling the family he wanted to help build the plant.

“I told him, if you go there to help, I will stand there with an anti-nuclear power plant sign all day. I will protest until they are forced to shut down," Landrigan recalled.

A nuclear war terrifies her because she can't visualize it. “It'll be the end of the world as we know it. If we don't take a stand now, we will soon be in World War III with nukes," she said.

Yet for some in the younger generation, Nhuch said, worrying about nuclear weapons isn't as important.

“Maybe we are an isolated generation. We've secluded ourselves from the world, and we don't care too much about what's going on out there," Nhuch said.

For Greene, however, the foreboding implications of a crisis thousands of miles away could affect him where he lives.

“Where would we go if tomorrow they said we had to evacuate because of war," he wondered. “I don't have a home. I don't have a family. I have nowhere to go."