“He was crying and crying and crying,” said Filonenko, 46, who fled Kyiv for Poltava, 350 miles away, to seek refuge among relatives. “I used all my knowledge to support him and to explain what was happening,” said Filonenko, a dermatologist who retrained in psychology after her son was born.

The crisis in Ukraine has unleashed a network of online mental health experts, some refashioning routine virtual care in response to the war; others providing psychological first aid for refugees or support for local therapists who suddenly find themselves on the front line of an evolving mental health crisis.

“We all — many, many professionals around the world — have mobilized to work with what’s going on there, with extensive psychological trauma,” said Galina Itskovich, a Brooklyn-based developmental psychotherapist who has been working with parents and professionals in Ukraine for several years. “We have a grass-roots movement here, getting connected very quickly.”

Itskovich, who has visited Ukraine several times since Russia annexed Crimea in 2014, said mental health experts are coordinating with nongovernmental organizations such as UNICEF and academic institutions to support local efforts and ensure guidance is available in Ukrainian and Russian. The coordination is crucial, experts say, to avoid volunteers’ hampering response efforts, as sometimes happens in disasters.

“We have to be very thoughtful about not contributing to resource strain,” said New York-based psychiatrist Sander Koyfman. “Things that can be done remotely should be done remotely to avoid a secondary disaster,” he said.

Volunteers also have to be trained in the specific strategies of psychological first aid. Everyday therapy typically addresses illness, helping to remedy abnormal reactions to normal events, therapists said. The reverse is true during a disaster: First responders provide resources to people who are having normal reactions to abnormal events.

“We don’t focus on illness, but on getting people grounded, to be as functional as one can be to survive and in the future to thrive,” said Koyfman, who serves on the American Psychiatric Association’s committee on the psychiatric dimensions of disasters.

The surges of adrenaline that can disable people in normal times have a special purpose during times of terror.

“You want people to be on edge, a little hypervigilant,” said Judith Bass, a psychiatric epidemiologist at the Johns Hopkins Bloomberg School of Public Health. “That is what will keep them safe and alive.”

Hopkins’s global mental health center has been working in Ukraine for about eight years, helping to build up resources within the country to support people displaced in 2014. They include creating an apprenticeship system for lay providers who are trained to offer every level of care.

The organizations and the volunteers involved in the work have an established playbook that is common to disasters the world over, including connecting with families to find ways to give children space to engage in normal childhood activities such as drawing, playing and singing while allowing their caregivers some release.

“We are keeping an eye on our providers,” said Laura Murray, a clinical psychologist and senior scientist at the Hopkins center. “That is one thing covid really taught us,” she said, explaining the toll taken on caregivers by the prolonged pandemic.

Some factors set the crisis in Ukraine apart, experts say. There is a large population of elderly people in Ukraine, many of whom cannot or will not leave their homes, putting additional strains on family members and caregivers who may want to flee.

Medical care has been more widely available than in many parts of the developing world, creating logistical challenges of refilling prescriptions for people whose pharmacies may no longer be operating or who are on the move.

Many of the U.S.-based mental health experts who are volunteering their services describe their sense of emotional solidarity, their common culture or elements of shared history with Ukrainians.

“This is very much near and dear to my heart,” said Koyfman, who is from Moldova and receives a continuous flow of messages from family and friends, which he melds with lessons from work he did after the 9/11 terrorist attacks, the 2004 tsunami in Sri Lanka and, most recently, with evacuees from Afghanistan.

Madlena Rozenblyum, a psychotherapist in Queens who came to the United States from then-Soviet Georgia in 1989, remembers how compelled she felt to help in 2014 as people fled Crimea. She began accumulating piles of toothpaste, sleeping bags, markers for children, until her husband stopped her.

“That is a great thing. But sit down,” he told her. “I think probably you can do more.”

Rozenblyum decided to write to colleagues, recalling for them the World War II story of two young Jews in the Terezin concentration camp north of Prague who organized underground mental health support for fellow prisoners.

“Somehow they realized that in order to survive, people need not only a piece of bread but emotional support,” Rozenblyum said.

Armed with that history, Rozenblyum put together a small group of Ukrainian volunteers to provide workshops on helping traumatized children, veterans suffering from post-traumatic stress and people who had fled their homes, as well as preventing burnout among mental health caregivers.

Her network became more active just before the Russian invasion last month. It puts out an online newsletter with tips on where to find food and transportation — resources that are more important than therapy in this acute stage of the assault, she said.

“We’re not talking about personal growth. We’re talking about survival,” she said.

Right now, she says, Ukrainians are on overdrive, experiencing a war that is moving far faster than conflicts of the past. “That is so overwhelming for the human body, brain, mind,” she said. “What in World War II took place in months, takes place in hours.”

The sudden change from the looming threat of war to an invasion prompted many Ukrainians to seek emotional support from friends and family members who had fled the country during earlier conflicts. Eugene Luciw, the president of the Philadelphia branch of the Ukrainian Congress Committee of America, whose parents immigrated to the United States, said Ukrainian Americans have been aware of a low-grade sense of stress for the past eight years among relatives who stayed behind.

“Everybody has been dealing with this as dull aching toothache of worry and concern,” Luciw said. Three weeks ago, when the pain became acute, the calls for support came pouring in via social media.

Itskovich, the psychotherapist in New York, got together online with the same group of parents Monday. She didn’t know where they would be or what they would tell her. When they last spoke, 10 days earlier, some were preparing to flee; others were afraid to leave their apartments even to go to a shelter, for fear of disturbing the equilibrium for the autistic children.

On Monday, Itskovich learned that over those 10 days, the disaster had become intensely personal. Parents who had been protecting their families from the sounds of bombs now had to draw on deeper resources — to console children who had witnessed the deaths of loved ones.

“At this point it’s hard to predict the worst that is going to happen,” Itskovich said. “They have been through unthinkable trauma and stress. Trauma is infectious. Trauma spreads.”