Ukraine and Russia Live War Updates: Latest News & Video

“We’ve been preparing for this for years,” said Yuri Scripts, a neurosurgeon who volunteered as a battlefield medic. He belongs to the medical battalion of hospitals, stationed here in this city in eastern Ukraine now a few hours’ drive from the reported positions of the advancing Russian forces.

In a brick warehouse converted into their headquarters, where a giant wood stove was blazing, volunteer medics spent Thursday packing backpacks and bags with emergency medical supplies, mostly just what was needed to stop the bleeding: a tourniquet, a clotting factor, bandages.

The Volunteer Doctors and Paramedics Organization has been working for years along the front line of the East Ukraine war, where Russian-backed separatists have been fighting Ukrainian forces. Volunteers ferry wounded military personnel to a civilian hospital to ease the burden on the military, and with a mixture of anger and determination they have prepared for what is perhaps a much larger task today.

“The whole world is weak,” said Mr. Scripts. “Putin didn’t really fight back, and that’s the result.”

On the wall hung pictures of eight volunteer medics from the group killed in the fighting in the east, which began in 2014 but has always been confined to part of Ukraine, in contrast to the broader offensive launched by Russia on Thursday.

Votive candles stood on a shelf below the photos, and some items to remember the volunteers: uniform spots, a small collection of jagged splinters, photographs.

Over the past year, the government of President Volodymyr Zelensky has attempted to formalize the work of these organisations, which range from non-governmental groups of moderate character to armed and politically active paramilitary groups, to a national group under a military command, called the Regional Defense Forces. This business rebounded last fall, when Russia mobilized its forces.

The defense forces, along with independent groups, are seen as the nucleus of a potential rebellion against the Russian occupation.

“A lot of ordinary people are ready to resist if the officials in Kiev surrender,” said Oleksandr Isenko, the volunteer paramedic. Has the medical wing of this movement drawn up plans to treat wounded fighters in secret locations? He replied, “No comment.”

All medical supplies have been donated, and doctors and nurses are volunteering their time, said Anna Vidianovich, the group’s deputy director.

“I think our army will not allow the occupation,” she said, but she did not seem too optimistic. Citing a statement President Biden made before the Russian attack, she said, “Russia has a list of volunteers and patriots” for arrest.

This means that people love it. She was worried that the members of the group would be quickly betrayed by neighbors in a town where pro-Russian sentiment prevails, should the Russian army appear.

“Everyone has a neighbor who is ready to betray them,” she said. “I don’t know how I can stay here and not be arrested, maybe even tortured,” she said. “It’s hard to imagine staying here.”