CHASIV YAR, Ukraine — On a clear spring morning eight years ago, Oleksandr Khainus stepped outside his house to go to work at the town factory when he spotted new graffiti scrawled across his fence. “Glory to Russia,” vandals had written in angry black spray paint. “Putin,” another message said.

Mr. Khainus was perplexed. It was true that Chasiv Yar, the Rust Belt-like town where he has spent his entire life in a region called the Donbas, had long contained many conflicting opinions on its identity. Geographically, the Donbas was part of Ukraine, no question, but it was so close to Russia and so tied to it historically that many maintained that their true home really lay eastward.

“It was the type of stuff you’d argue about over the dinner table,” he said. “But nothing that anyone would get violent over.”

Mr. Khainus’s optimism now seems almost quaint.

In the next few months in 2014, pro-Russia protests exploded. Armed separatists seized chunks of the Donbas including Chasiv Yar right under the authorities’ noses. Two so-called People’s Republics were declared. Russian troops stormed in.

Vladimir V. Putin, Russia’s leader, turned this patch of Eastern Europe into a personal project, sowing the seeds for an explosion of bloodshed that would spawn the most far-reaching war in generations. It was the Donbas that became Mr. Putin’s pretext for a full-scale invasion of Ukraine. And now it is heating up again.

The Ukrainians have just pulled off a masterful offensive in the Kharkiv region, in Ukraine’s northeast, where town after town fell without a shot. Now they are heading south. Columns of dark green military trucks and American-made rocket launchers are thundering down the long, straight highways into the Donbas. But they will have a much harder fight on their hands.

The Russians have been dug into the Donbas for nearly a decade. They have countless fallback positions, fortified trenches, tens of thousands of soldiers, mercenaries from the notorious Wagner Group and close air cover because of the proximity to the Russian border. They can also rely on separatist fighters and a well-financed network of citizen-spies who relay secret information to the invaders, often with devastating consequences.

“Our walls now shake every day from shelling,” said one Ukrainian soldier on the front lines who could not be identified because of the sensitivity of his position. He said that the Ukrainian military was taking heavy casualties in the Donbas and that “the Russians storm us every day and seize our territory by a couple of meters a day.”

In Soledar, an old salt mining town, earsplitting explosions crack in every direction. Black smoke thickens the air. Civilians are refusing to evacuate, disobeying a direct order from the Ukrainian government to get out of the way of the incoming troops. Places like this have become a snake pit. The troops do not trust the people. The people do not trust the troops. Nobody trusts anybody.

“I’m not going,” declared one woman on a recent afternoon as she clutched the side of her shrapnel-pocked house. Her voice shook at the edge of control. She had a wild look in her eyes. “I’ve been here 40 years,” she yelled over the sounds of the explosions. “My ancestors are buried here. Where are our boys to defend us? Why aren’t they here?”

To understand the Donbas, and how it became the benighted chunk of territory that Mr. Putin wants so badly, is to see it as an integral piece of a grand strategy to resurrect elements of the Soviet world. Some people living here welcome that; others cannot imagine anything worse.

The region is full of contradictions like these, both rustic and industrial, beautiful and blood-soaked, enormously important to the national economy but in terminal decline. For the past eight years, Mr. Putin has poured in money, spies, propaganda and weapons, thoroughly destabilizing this complicated corner of Ukraine.

Then, on Feb. 24, 2022, he turned its problems into a global crisis.

The Donbas region used to be part of what the Russians called “Dikoye Polye,” or the Wild Field. Even today, driving in past millions of sunflowers tracking the sun across huge blue skies, the Donbas still exudes an epic sense of space.

For centuries, the Wild Field was loosely controlled by Asiatic tribes and Cossack groups. But in the late 1700s, Catherine the Great, the Russian empress, colonized it with hearty souls from across the empire. In the 1800s, the Russians built a steel industry here, remaking the landscape. They left enormous mountains of slag on the horizon and dug pits for clay so yawning that they eventually filled with rain and became lakes.

Chasiv Yar became home to a large ceramics plant. It grew into a typical Donbas industrial town — one that would encapsulate all of this region’s warring feelings. Mr. Khainus, who has deep green eyes and permanently tousled hair, took his first job here 23 years ago, sorting bricks. “It was exhausting,” he said. “But my hands got really strong.”

Mr. Khainus is not what I had expected to find in the Donbas. Many people had told me, before I arrived in July, that the only people still living here were those who sympathized with Russia, derisively referred to as “the Waiters” because they were believed to be waiting eagerly for the Russians to come.

But Mr. Khainus, who grew up speaking Russian (like many here) and has deep family roots in this part of Ukraine, said, when asked if the Donbas should be part of Russia: “Are you kidding? That would be a complete disaster. There would be no development, no normal life, no law.”

Instead, he serves as a local representative for Power of the People, a liberal political party trying to pull Ukraine away from Moscow’s clutches. He has moved on from the ceramics plant, which shut down a few years ago. Now he farms sunflowers.

Across the street from him stands a yellow brick house where, some other townspeople had complained, a rabidly pro-Russia separatist lived. I knocked on the gate.

An older man hobbled out. When my translator, Oleksandra, told him I was an American journalist, his whole face lit up. “Amerikanski!” he blurted and gave me a bear hug. He was shirtless, it was warm, and his skin was damp with sweat.

He introduced himself as Volodymyr Tsyhankov. He talked fast, a huge smile on his face, and said that he used to be a champion sprinter and Chasiv Yar’s top arm wrestler. He had a broad chest and thick biceps. At age 70, he looked like he could still do some damage.

Mr. Tsyhankov, too, had worked at the ceramics plant, driving a dump truck, and clearly missed those days. “We had good work, a decent salary,” he said.

He and his wife, Liudmyla, said they had built a good life in Chasiv Yar. Fishing for pike, perch and catfish in the man-made lake behind their house; growing grapes, apples, beets and plums in their backyard plot; canning the fruit for the long winter; raising children and grandchildren.

“Life under the Soviet Union might not have been good,” Ms. Tsyhankova said, looking into her husband’s eyes for affirmation. “But it was stable.”

I heard this a lot.

When the Soviet Union disintegrated in 1991, Ukraine became an independent country. For younger people, this spelled new opportunity. But for Mr. Tsyhankov’s generation, it was like a crash of their whole life project.

In February 2014, protesters in Kyiv, the Ukrainian capital, chased Viktor Yanukovych, Ukraine’s pro-Russia president, out of office. Mr. Yanukovych came from a Donbas steel town. In one stroke, Russia lost its ally and the Donbas elite its godfather. That is when the trouble started.

People flooded into the Donbas streets waving Russian flags. At first, said Alisa Sopova, a journalist for a Donbas newspaper at the time, “We were sure they were fake people brought in from Russia to pose for Russian TV.”

“But when we went out and talked to them,” she said, “we learned they were locals, working-class people, mostly. And it was frustrating. They were just falling for manipulation, and we knew they’d suffer for it.”

Ms. Sopova, who is now studying anthropology at Princeton, tried to reason with some of them, including her grandmother. “I told her: ‘You’re using banks. You’re getting your pension. Do you realize what you’re supporting will destroy it all?’”

But they did not listen.

“They didn’t know it would turn out this way,” she said. “And now it’s too late.”

In Chasiv Yar, it was like a poison had been injected into the town’s bloodstream. The issue of language suddenly became fractious. Ukrainians have argued forever about whether it is right to speak so much Russian. A critical aspect of Ukrainian independence was reviving the Ukrainian language, marginalized during Soviet times. But those arguments were typically confined to social media posts or intellectual debates, until this moment.

“I’d go into the supermarket to buy some meat, and the shopkeeper tells me, ‘If you don’t speak Ukrainian, I’m not going to sell you any meat,’” Mr. Tsyhankov said. “I’ve been speaking Russian my whole life. How do you think that made me feel?”

He looked down at his hands, humiliated even by the memory.

What became clear only later was that all of this had been orchestrated. Mr. Putin had done something similar in 2008 in South Ossetia and Abkhazia, two regions of Georgia, and before that the Russians had meddled in Moldova, backing the breakaway Transnistria region. The tools were generally the same: bankrolling pro-Russia political parties; deploying intelligence agents to foment protests; sowing disinformation through Russian TV.

Mr. Putin’s strategy was to turn strategic slices of the former Soviet Union into separatist hotbeds to hobble young nations like Georgia, Moldova and Ukraine, all struggling to break free from Moscow and move closer to Europe.

Under the Kremlin’s wing, Donbas’s separatists killed Ukrainian officials, took territory and declared the breakaway Donetsk People’s Republic and Luhansk People’s Republic. When Ukrainian forces rolled in to quell the rebellion, some residents saw them as occupiers. They spoke a different language, hailed from a different region, embraced a different culture — or so went the pro-Russia narrative. In some villages, babushkas lay down in the roads blocking Ukrainian tanks, officers said, and in one, an especially cunning babushka kept stealing the soldiers’ helmets.

“It was frustrating,” said Anatolii Mohyla, a Ukrainian military commander. “We’d come to liberate them and they’d give us the finger.”

Mr. Putin dispatched thousands of Russian troops to support the separatists, later saying he had been “forced to protect” the Russian-speaking population. Towns like Chasiv Yar were occupied by separatist fighters, then liberated by Ukrainian troops a few months later. By 2015, the heavy fighting had died down. But it was not like Mr. Putin forgot about the Donbas.

He upped the ante in 2021, saying, “Kyiv simply does not need the Donbas.” And on Feb. 21 of this year, three days before he invaded Ukraine, Mr. Putin accused the Ukrainian government of perpetrating a “genocide.” He justified the most cataclysmic war in decades by citing the very tensions he himself stoked.

In early April, the agricultural land around Chasiv Yar began to thaw. Mr. Khainus, the pro-Ukraine farmer, drove out to check a sunflower field. A Ukrainian military vehicle raced up. A soldier leaned out the window and fired an assault rifle, the bullets skipping up in the dirt. Mr. Khainus slammed on the brakes.

A Ukrainian commander he recognized, a man whom Mr. Khainus said he had complained about before, jumped out. The commander greeted him with a punch to the head, Mr. Khainus said, and then smashed him in the face with a rifle butt.

He does not remember much after that. He shared photographs of himself lying in a hospital bed with two black eyes. Military and law enforcement officials declined to comment.

Mr. Khainus remains a supporter of the military, saying, “One stupid person doesn’t represent the army.”

But, he added wryly: “It’s one thing to be a patriot in Kyiv. It’s another to be a patriot in the Donbas.”

At 9 p.m. on July 9, four cruise missiles slammed into a dormitory at the old ceramic plant. The buildings crumbled as if they were made out of sand. Viacheslav Boitsov, an emergency services official, said there were “no military facilities nearby.”

But according to Mr. Mohyla and Oleksandr Nevydomskyi, another Ukrainian military officer, Ukrainian soldiers were staying in that building. The night before, they said, a mysterious man was seen standing outside flashing light signals, most likely pinpointing the position.

The military calls such spies “correctors,” and they relay navigational information to the Russians to make missile and artillery strikes more precise. Ukrainian officials have arrested more than 20 and say correctors are often paid several hundred dollars after a target is hit. The strike in Chasiv Yar was one of the deadliest: 48 killed, including 18 soldiers, the officers said.

“For sure there are Russian agents in this town,” Mr. Mohyla said. “There might even be spies in our unit.”

Few in Chasiv Yar are confident that the town will stay in government hands.

Mr. Khainus said the Russians were steadily moving closer to his sunflower fields. About a week ago, a friend’s house was shelled. A day later, in an online messaging channel, separatist supporters said Mr. Khainus should be next, calling him a “hero” — adding an epithet.

Is he scared?

“Why should I be?” he said. “They’re nobodies.”

Mr. Tsyhankov, the retired dump truck driver nostalgic for the Soviet times, seemed pained by all of the bloodshed but did not blame the Russians or the separatists. “They’re doing the right thing,” he said. “They’re fighting for the Russian language and their territory.”

As he said goodbye, insisting that his guests take with them a jug of his homemade apple juice and some fresh green grapes, he shook his head at the enormity of it. “Why can’t we be friends with you guys, the Americans?” he asked. “Politics are keeping all of us hostage.”

Every night, the horizon in Chasiv Yar lights up with explosions. Ukrainian soldiers operate here almost as if they are on enemy territory, hiving themselves off from the public, watching their backs, traveling by night in long convoys of cars with the lights blacked out, the drivers wearing night vision goggles. According to separatist messaging channels, the Wagner mercenaries have reached the outskirts of Bakhmut, a major Donbas town. As for Soledar, it is now off limits to journalists, but volunteers there trying to rescue civilians say it is as deadly as ever.

People here used to describe the Donbas in simple terms like “beautiful,” “honest,” “unbreakable” and “free.”

Now it is destroyed, depopulated, sad and empty.

“It’s like the Rust Belt,” Ms. Sopova said. “It’s not needed anymore. All that industry is obsolete.”

Countless communities have risen in the Donbas. Many are now falling. Ms. Sopova glimpses a perhaps not so faraway future where the Donbas goes back to what it once was: a wild field.

Oleksandra Mykolyshyn contributed reporting.