TYKHONOVYCHI, Ukraine — The deep trenches and scattered observation posts that marked Ukraine’s northern border with Russia were no match for the columns of tanks that rolled across on Feb. 24.
The war here is different from elsewhere in the country, where Russian troops are firmly ensconced in Ukrainian territory. This is a cross-border war. Russian tanks lob shells at Ukrainian villages. Bullets fly across a tense no man’s land in sporadic gunfights.
“The border will never be the same,” said Serhiy Khomenko, 30, commander of a unit patrolling the border near the village where he grew up. “If before there was just a tank moat, now the whole thing will be mined.”
Khomenko and his subordinates don’t get days off anymore. They live in the swamps and forests that line the border, battling not just the Russians but “knuckle-sized mosquitoes.” The coils they burn in the trenches to keep them away used to make them dizzy, he said. Now they’re used to it.
Seven weeks have passed since the Russians withdrew from the Chernihiv region. Winter has turned to spring, and tens of thousands of displaced people have returned as roads and public services are restored.
Border officials say it’s all happening too soon. Between two and eight shells land in the Chernihiv region every day, said Oleksandr Sereda, deputy commander of the region’s border guards. Ukrainian troops are regularly forced to return fire across the border.
“In any case, we are preparing for a possible reinvasion,” he said. “They are attacking our positions and towns. [The Russians] have no concept of the rules of engagement.”
The same dynamic is playing out in the neighboring Sumy region, which the Russians vacated around the same time as Chernihiv. And in Kharkiv, as Ukrainian forces push the Russians back to the border, local officials said they expect the war there, too, to transform into one where defensive preparations replace pitched battles.
Relations between locals along both sides of the border were close but strained before the invasion. Familial and cultural ties are deep, but Russia’s annexation of Crimea in 2014 as well as its support of separatists in eastern Ukraine created tension, even hundreds of miles away.
“Previously, relatives, friends and acquaintances came here from Russia with good intentions,” Khomenko said.
After the invasion in February, all that became unthinkable.
“Now, the border is sprinkled with rivers of blood. It is a memorial to those who died. This line is now associated with sacrificed lives,” Sereda said.
In Tykhonovychi, a village of about 600 residents separated from the border by half a dozen miles of forest, two local young men serving in the border guard were killed in the final days before the Russians withdrew.
Andriy Samusenko and Anton Myahkyi were childhood friends. They were both 30 years old, with blue eyes, and left behind adoring families.
Their colleagues know exactly how they died, because the Russian soldiers who ambushed them had their cameras running and posted the footage on Telegram.
The video shows Russian soldiers firing a rocket-propelled grenade at the border guards’ pickup truck, then summarily executing those who survived.
Samusenko’s wife, Nina, 35, is now raising their five daughters on her own and is three months pregnant. She and Andriy conceived on the eve of the war, before he deployed. She is hoping her sixth will be a boy.
Neighbors have tried to help her, but she is too stricken with grief to engage. When visited by reporters, all she could say about her husband before being overcome by tears was: “He was the best.”
Down a dirt road about a mile from the Samusenkos’ house, the Myahkyi family gathered to receive three of Anton’s fellow border guards who were visiting to lay flowers at his grave.
His grandmother, Halyna Petrivna, 68, was particularly fond of him. She knows the exact number of days since Anton was killed, since he was buried, and since the invasion. She is grappling with the same question so many Ukrainians have struggled to answer: “Why?”
“So many young people have been lost, and what for?” Petrivna asked. “I don’t understand their purpose. Why are they bombing nonstop? What do they expect? That we surrender?”
People in Tykhonovychi and other villages are instead giving everything they have to the border guards. They cook all their meals, and civilians man outposts if the guards are stretched too thin.
“If you tell them that you need milk, they will bring you a vat,” said Khomenko, the commander.
Having seen how easily the Russians barged across the border once, most here are girding for another round.
“People are wary. They hear that Russians have increased their strength again,” said Anatoliy Bondarenko, 45, the village’s mayor.
On the day of the invasion in February, Bondarenko got word from a village closer to the border that the Russians were on their way. He called everyone he could to tell them to hide. Then he hid all the documents he could.
Three tanks rolled in and knocked a power pole down. Some locals came out to confront the Russian soldiers, who they recalled as acting confused, even lost.
A short argument ensued, but then the Russians were on their way — eventually reaching the outskirts of Chernihiv, a city of 300,000 that they encircled but never took over. Over the course of March, Russian jets and artillery bombed and shelled the city pitilessly. The border guards’ headquarters was hit at least 30 times and badly damaged, but the majority of targets served no military purpose — apartment buildings, grocery stores, schools. More than 700 civilians were killed there, according to the city’s mayor.
In the villages, the biggest change has been their attitude toward the border. Once, it had been an imaginary line, an accident of history, nothing to worry too much about. Now they see it as the only thing between them and a horde of invaders.
“After the big war started, even those who have brothers and sisters in Russia have stopped talking to each other,” said Bondarenko, whose wife is originally from a village in Russia. A friend of hers called recently to say that she didn’t believe Chernihiv had been bombed and that Ukrainians should watch Russian channels to learn the truth.
“Sometimes when I turn on the TV to watch Russian channels, I feel it is necessary to have nerves, it is necessary to be mentally healthy. A man with weak nerves can break a TV,” Bondarenko said. “It is impossible to watch. I just turn it on, I get mad immediately, and then I turn it off. They are just zombies now.”
Serhiy Morgunov contributed to this report.
An earlier version of this article misidentified the deputy commander of the Chernihiv region’s border guards. His name is Oleksandr Sereda, not Oleksandr Vadovsky. The article has been corrected.