YUROVE, Ukraine — Fears have grown along Ukraine's northern border about the potential for new military attacks since Yevgeniy Prigozhin's Wagner mercenaries relocated to Belarus after last month's short-lived mutiny against Moscow's military leadership, with Ukraine — and even Poland — tightening security and stepping up defenses.

Belarus served as a staging ground when Russian President Vladimir Putin launched his wide-scale invasion in February 2022, including a failed assault on Kyiv, the Ukrainian capital. Defeated Russian units then retreated back across the Belarusian border.

Putin's decision to allow Prigozhin and his fighters to escape punishment for the rebellion by relocating to Belarus prompted Ukrainian President Volodymyr Zelenskyy to direct the military and national security forces to beef up defenses in the north.

The State Border Guard Service has since moved in additional personnel, and the military has strengthened its fortifications with additional antitank and antiaircraft systems, said Lt. Gen. Serhiy Nayev, who has operational control over the "North" group of the Ukrainian armed forces.

Heavily mined border areas have been seeded with more explosives, and many bridges on routes leading to Belarus that were destroyed earlier in the war have not been repaired. In recent days, Ukrainian forces also blew up portions of a highway running from Kyiv to Belarus, Nayev said, adding that he felt "confident" in Ukraine's protective measures.

But all of this activity has heightened unease among residents along the border, where anxiety was already growing after a decision by Putin earlier this year to station nuclear weapons on Belarusian territory.

"Of course we're worried," said Oksana Kozub, 50, sitting outside her home here and chatting with friends who had driven their cart to the town's post office.

Kozub said her memories of last year's invasion — when Russian fighter jets and rockets flew over this village about eight miles from Belarus to strike Ukrainian targets in the region — are still fresh. Yet she said she has little recourse if violence spills over the border again. "Where am I going to go?" she asked.

Poland has also strengthened its eastern defenses after Prigozhin arrived in Belarus and his mercenaries launched joint military training exercises with Belarusian security forces near the Belarusian border city of Brest, the Polish Defense Ministry said in a post on Twitter.

In response, Putin warned during a meeting with his Security Council last week that any "aggression" against Belarus would be considered an attack on Russia, and that Moscow would retaliate "with all the resources available to us," according to the official Kremlin transcript.

Nayev, the general, said Ukraine's military was even allowing the possibility, however far-fetched, that Putin might authorize the use of tactical nuclear weapons while making it appear as if Wagner mercenaries were to blame for a rogue attack.

That scenario has been advanced by Vadym Kabanchuk, deputy commander of the Kastus Kalinouski Regiment, a unit of Belarusians fighting in Ukraine against Russia. Kabanchuk, at news conference this month, warned that it is the kind of sleight of hand Putin, as a former KGB officer, could use to do the unthinkable.

"We are considering all scenarios," Nayev said in an interview while attending a training exercise for the military and national guard held inside Chernobyl Exclusion Zone near the stricken nuclear power plant to simulate an attack by saboteurs. The exercise, using live explosives, also featured U.S.-made MaxxPro mine-resistant armored vehicles.

On Sunday, Putin also met the Belarusian leader, Alexander Lukashenko, who has effectively turned his country into a Russian client state. Lukashenko was credited by the Kremlin with brokering the truce that halted Prigozhin's "march for justice" against Russia's military leaders.

Since then, Lukashenko has welcomed Wagner to Belarus, where hundreds of fighters have begun training Belarusian military and security forces.

During Sunday's meeting in St. Petersburg, Putin praised the two countries' strong economic ties and characterized Ukraine's counteroffensive as a failure. Lukashenko used the get-together to troll Poland, saying Wagner fighters were itching to invade.

"They are asking permission to go west," Lukashenko said, according to the Kremlin's official transcript. "They say on the sly . . . 'We will go for an excursion to Warsaw and Rzeszow.'"

Earlier this month, Prigozhin — appearing in a video verified by The Washington Post — welcomed his fighters to Belarus and vowed to turn the Belarusian military into "the second army in the world."

Recent satellite images provided by Maxar Technologies also show what appears to be a Wagner garrison in Tsel, a village southeast of Minsk that is less than 150 miles from the Ukrainian border.

Belarus has been a wild card in European security since Putin began massing troops on Ukraine's border more than two years ago. In October 2021, Russian and Belarusian militaries conducted their largest joint military exercises in years in Belarus and the Black Sea. Months later, Moscow invaded Ukraine.

Senior officials in Kyiv, however, have played down the threat from Wagner's presence in Belarus, given estimates that their numbers are small and amid signs of chaos within their ranks.

"In Belarus, there's only a small group of Wagner forces," Mykhailo Podolyak, one of Zelenskyy's top advisers, said in an interview last week. "They're training the Belarusian special forces. What for isn't completely clear."

Podolyak speculated that Lukashenko might be hoping that Wagner's hardened fighters will train his own palace guards.

Ukrainians who live along the Belarusian border have responded with alarm to Wagner's redeployment next door. Yet they also remember when Belarusians and Ukrainians traveled back and forth across the border with relative ease at crossings such as Slavutych, just east of the Dnieper River in the Chernihiv region north of Kyiv.

"This was quite a lively checkpoint," said Lt. Col. Halyna Shekhovtsova, a press officer for the Chernihiv region's border guard detachment. About 500 vehicles a day, and many pedestrians, crossed daily for business or pleasure, Shekhovtsova said. Weekends were particularly busy for Belarusians, who visited Ukraine to buy less expensive clothing in the latest fashions or, they told her, simply because "you have freedom here."

Now, the border station is overgrown with weeds. On the morning of Russia's invasion, Ukrainians blew up the bridge carrying vehicle traffic over the Dnieper River, about 500 meters (a third of a mile) from Slavutych. A parallel railroad line was blown up, too, and mines were strewn throughout the nearby woods.

The area has been quiet since the early days of the war, but border guards are on alert. "We are watching that closely," Shekhovtsova said.

In Dniprovske, a village of fewer than a thousand people about three miles from the checkpoint, residents worry that Wagner fighters might infiltrate across the river or mount other cross-border attacks. Their more likely concern is Russian airstrikes, such as a July 21 attack that killed two people in Goncharivske, a village about 18 miles away.

"I actually heard the explosions," said Serhiy Lubenko, 63, a retired factory worker who was picking mushrooms in a forest nearby at the time. But Lubenko, sharing vodka and snacks with others outside a village market, said Ukraine's military seemed to have the northern border under control.

"The Wagners wouldn't dare," said Sonya Pasuchnyk, 78, who walked to the market for bread. But she, too, is uneasy, having sheltered in her root cellar with her dog last year when jets and rockets bombed targets near the village. "I never would have thought such a thing possible," Pasuchnyk said.

West of the exclusion zone that surrounds the shuttered Chernobyl nuclear power plant, the site of a catastrophic accident in 1986, concerns about possible trouble emanating from Belarus are sharper, owing to a long border and fewer natural obstacles.

Natasha and Yuriy Dobrovec, who live in Kopyshche — a village surrounded on three sides by the Belarusian border less than two miles away — said the region has been relatively calm since last year's invasion.

But the war has been felt in other ways. Their son, Petro, 38, and his wife, Maria, 32, were killed when their car, traveling near the border on a wintry day seven months ago, slid off a narrow road and hit a mine. Their two orphaned children have been placed in the care of an uncle.

Now, the Dobrovecs watch recent developments with worry. "We live 100 meters from the border and we haven't seen anything," said Natasha, 60, who was born in Belarus but has lost contact with relatives there since the invasion. "But who knows?"

The Washington Post's Sarah Cahlan, Anastacia Galouchka, John Hudson and Kostiantyn Khudov contributed to this report.

previous coverage

• Prigozhin says Wagner mercenary group for now will not fight in Ukraine
• Prigozhin faces lawsuit over alleged Wagner executions in Libya

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