President Donald Trump's avowal to unleash "fire and fury" on North Korea in response to any military strikes against the U.S. has raised the spectre of a nuclear confrontation between the countries, ratcheting up public anxiety about the potential for such a devastating event.
While the escalating rhetoric may be mere sabre rattling, psychologists say feeling fearful or anxious about the threat of a nuclear holocaust or any life-altering catastrophe is perfectly normal.
"Sometimes we might experience a sense of being in constant danger, especially if we're questioning if there's this threat to life and safety," said Dr. Katy Kamkar, a clinical psychologist at the Centre for Addiction and Mental Health in Toronto.
"And it becomes not only the concern for the safety of self, but then of course for the safely of loved ones, the destruction of everything we have established," she said.
"The uncertainty can induce more worry. We feel more vulnerable and it can lead to feeling more helpless and powerless."
Shmuel Lissek, founding director of the ANGST Laboratory at the University of Minnesota, said humans have been hard-wired to err on the side of caution.
From an evolution perspective, organisms that were overly cautious in the face of low-probability threats were more likely to survive and pass on their genes — and humans inherited those genes, Lissek told the Washington Post this week.
"So when there's a very small-probability threat that is of very high intensity, we tend to worry instead of not worry," he said.
A person's age may also dictate how they react emotionally to the perceived threat of nuclear war, Kamkar said.
Many baby boomers grew up during the Cold War, when then U.S. president John F. Kennedy and Soviet premier Nikita Khrushchev took the world to the brink of a nuclear conflagration with the 1962 Cuban Missile Crisis, and the fear of annihilation was a seminal event in many of their lives.
In his 2001 book A Cook's Tour: In Search of the Perfect Meal, New York-born chef Anthony Bourdain, 61, wrote: "I grew up thinking the Big One could come at any moment, and this country — or fear of it, the way my country reacted to the threat — radicalized, marginalized and alienated me in ways that still affect me."
While younger adults did not share that experience with their parents or grandparents, later military conflicts with or without the risk of weapons of mass destruction may have increased their psychological sensitivity to a perceived threat of atomic war.
For instance, a study of Finnish students aged 15 to 19 around the time of the 1991 Persian Gulf War — in which a U.S.-led international coalition defeated Iraq after its invasion of Kuwait — found those adolescents who frequently worried about nuclear war had an increased risk of having developed a mental health disorder five years later.
Kamkar said teens and children process events differently than adults, "but we know children look to their parents. So if they see any fear or panic within their parents, they might in turn feel it as well.
"Also we know that if they hear it through the media ... it can then in turn induce those negative or frightening images in them."
Richard John, an associate professor of psychology at the University of Southern California, agreed the war of words between Trump and North Korean dictator Kim Jong Un in the media can exacerbate public anxiety.
"I think people react to the news a lot more strongly now because it's hard to escape," he said Thursday from Los Angeles. "In the '60s, you heard one news report for half an hour at night and that was about it. And now, it's a 24-hour news cycle.
"You go on social media and you go on anywhere and you're just bombarded with the media talking about this. And it gets amplified."
John, associate director of research at the Center for Risk and Economic Analysis of Terrorism Events — or CREATE, established by U.S. Homeland Security — is an expert in what's known as probabilistic risk assessment. He suggested people do seem to have a heightened sense that some sort of attack is imminent.
"I think right now they see the Korean dilemma as just part of the whole crazy Trump presidency ... and so probably most people just think the North Koreans are reacting to Trump's tweets ... and they don't see it in the context of the last 25 years of foreign policy towards the North Koreans.
"My sense right now is most people really don't appreciate much about history," he said, noting that former president Bill Clinton began that policy by giving North Korea US$5 billion in exchange for its promise not to pursue a path of nuclear armament.
And unlike in 1962, when both the U.S. and the Soviet Union were rapidly stockpiling nuclear weapons, there were no defensive weapons to knock down intercontinental ballistic missiles carrying those warheads, as is the case today, John said.
"So from an objective standpoint, if you asked what is the level of threat, what's the risk, how likely is this to happen, people should be a lot less anxious today than they were in 1962 during the Cuban Missile Crisis."