STETSKIVKA, Ukraine—Ukrainian troops said they are moving to encircle an estimated 3,000 Russian troops that are hemmed against a river in Russia’s Kursk province, seeking a fresh blow against Moscow in the third week of a surprise incursion.
Ukraine’s military said it used U.S.-supplied Himars rocket systems and explosive drones to strike pontoon crossings and bridging equipment as Russia scrambled to prevent the encirclement of its forces between the Seym river and the Ukrainian border.
Ukraine’s Aug. 6 incursion has embarrassed Russian President Vladimir Putin by seizing dozens of towns and villages across a territory as large as any Russia has captured in a year of offensives in Ukraine. Kyiv’s forces are now expanding their control along the border and striking Russian supply routes, as Moscow is ramping up counterattacks using massive glide bombs and troops rushed in from Ukraine and other parts of Russia.
The incursion hasn’t, so far, shifted the dynamic on the war’s main battlefields in eastern Ukraine, where Russia is advancing in toward Pokrovsk, a key Ukrainian logistical hub, and Toretsk, a city on strategically important high ground.
Meanwhile, Russian authorities said Wednesday they had thwarted a barrage of drone attacks on Moscow and other regions. Russia’s Defense Ministry said it had destroyed 45 drones deployed by Ukraine, including 11 that were shot down over the Moscow region.
In Kursk, Ukraine is stretching the breadth of its incursion rather than seeking a deeper advance that would be easier to cut off, said Mick Ryan, a military strategist and retired major general in the Australian Army.
“They are holding more-defensible terrain that’s closer to Ukraine and easier to support,” said Ryan.
Ukraine’s intent to hold what officials have called a buffer zone poses a dilemma to Putin as to whether to try to oust forces in what could be a costly operation. Such an effort would require pulling sizable forces from Ukraine, weakening promising offensives against strategic targets in the east and potentially opening gaps for Ukrainian troops to exploit.
For now, Russia appears mostly to be transferring forces from reserves and areas in Ukraine where fighting isn’t as intense, such as the south or the northeast.
“There’s a case for the Russians to see how this develops and to throw just enough at it to slow the Ukrainians down,” said Ryan.
For Russia, recapturing all of the Kursk region may be a secondary goal to the more strategic aim of advancing farther into the eastern Ukrainian province of Donetsk, which Putin has declared part of Russia. Moscow has been recruiting some 25,000 men a month but suffers from a shortage of experienced soldiers of the kind needed to push the Ukrainians out.
There is little panic in Moscow around the situation in Kursk, said Tatiana Stanovaya, a senior fellow at the Carnegie Russia Eurasia Center. Putin, she said, sees Ukraine’s offensive there as having little effect on his broader strategic calculus, which centers on seizing all of Donetsk and, eventually, bringing about the collapse of Ukraine’s government to ease the path to negotiations that favor Russia.
Stanovaya said the Russian military doesn’t want to be lured into a costly Kursk offensive that may require the kind of scorched-earth strategy previously used in Ukrainian towns such as Avdiivka and Bakhmut. Adopting the same tactic against Russia’s own towns in Kursk, where some civilians still remain, isn’t a defensible policy.
“If he doesn’t find a military solution then this may go on for months or a year,” she said of Ukraine’s foothold inside Russia. “And people in Moscow have got used to this idea.”
Still, the Ukrainian operation has dealt a blow to Putin’s pledge that the war he calls a “special military operation” will be confined to Ukraine and have a minimal effect on the lives of ordinary Russians. Some of Ukraine’s military command have long argued that making Russians feel the war should be a key part of Kyiv’s strategy, because it increases the pressure on Putin to end it.
“We want to bring the war to their territory,” said the commander of a drone battalion in Ukraine’s 14th Regiment who has the call-sign Cold.
Cold’s drone units were among the first troops who entered Kursk and are now hunkered down in the basements of homes north of Sudzha, using their reconnaissance and strike drones to help Ukrainian forces blast their way forward.
He said Russia is putting up a stiffer fight. Earlier this week, it sent a force of 80 men into one of the Ukrainian-held villages, dropping 21 glide bombs on the settlement in the space of an hour in advance of its assault, which Ukraine repelled with difficulty.
“We’re paying a price too,” Cold said.
The troops Russia is bringing in are well-equipped, Cold said, and some clearly have extensive combat experience. Russia has also successfully used its electronic warfare systems to down some of his unit’s drones. He can see from the drones’ feeds how some Russian troops are digging in and establishing defensive positions along the new front line, clearly expecting a lengthy campaign.
The barrage of drones Ukraine sent to Russian regions Wednesday comes as Kyiv has been stepping up attacks on airfields to prevent Moscow from using them to launch its own drones and warplanes. Last week, Ukraine conducted what an official described as the largest drone attack on Russian military airfields since the start of the war, with strikes in Voronezh, Kursk, Savasleyka and Borisoglebsk.
Cheaper and more available than cruise missiles, domestically produced drones enable Kyiv to get around political constraints on using weapons supplied by Western allies in attacks deep inside Russian territory. Ukraine has also targeted Russian oil refineries with its drones.
In Sumy, a city in the Ukrainian region bordering Kursk, the roads are lined with military vehicles that are being used to ferry supplies into Kursk, including food and fuel for the troops. They also are bringing in generators as damage to infrastructure in the Kursk region means there is no electricity there.
As the Russians assemble pontoon bridges to try to cross the Seym, the Ukrainians are smashing them with artillery. Pvt. Andriy Brigadir of Ukraine’s 44th artillery brigade, which operates Western-supplied M777 artillery guns, said the Russian river crossings are often conducted in a panicked way that exposes them to Ukrainian fire.
“The Russians are rushing in any men they can get right now,” he said.
Those men now include marines from Russia’s Black Sea fleet, normally based far to the south in the Russian-held Crimean Peninsula, according to the Russian Defense Ministry. On Tuesday, the ministry also announced the creation of three new military formations tasked with defending Kursk province and two neighboring regions.
Ukrainian soldiers say that is unlikely to help the Russian soldiers severed from their supply lines near the Seym river.
“Now that we’ve blown three of their bridges, it’s only a matter of time before this pocket closes for them,” said the commander of a reconnaissance unit in the 14th Regiment who has the call-sign Croat.
Jane Lytvynenko, Isabel Coles and Ann M. Simmons contributed to this article.
Write to Matthew Luxmoore at matthew.luxmoore@wsj.com and James Marson at james.marson@wsj.com
