SUMY, Ukraine—In Russia’s Kursk region just north of here, Russian assaults are so intense that their infantrymen sometimes step on the bodies of fallen comrades, according to Ukrainian soldiers opposing them there.
Russian glide bombs weighing one ton crash onto Ukrainian supply roads. Ukraine launched a flurry of Western missiles in the opposite direction last week, apparently injuring a North Korean general.
“They’re assaulting all the time—morning, day, night,” said Geniy, a 30-year-old battalion commander with Ukraine’s 47th Mechanized Brigade.
The battle for control of the Kursk region has reached an intensity rarely seen during 2½ years of war, as each side tries to strengthen its position before President-elect Donald Trump, who wants both sides to negotiate, takes office in January.
Moscow has deployed some 45,000 troops to the region, according to Ukrainian officials, including some of its best forces who are attacking in nonstop waves. Despite enormous casualties, the strategy appears to be working: In recent weeks, Russia has retaken nearly half the territory that Ukraine seized during its August incursion. Analysts say Russia might be planning an even bigger offensive there.
But Ukraine has also sent many of its best brigades to Kursk. In addition, President Biden’s decision last week to allow Kyiv to fire long-range American missiles into Russia has given Ukrainian troops a much-needed boost and a capability that could disrupt Moscow’s supply and command lines.
Trump’s pick to be national security adviser, Rep. Michael Waltz (R., Fla.), said he had met with his counterpart in the Biden administration, and on Sunday expressed some support for the recent decision to provide Ukraine with long-range missiles, as well as land mines.
“For our adversaries out there that think this is a time of opportunity, that they can play one administration off the other, they’re wrong,” Waltz said, speaking on Fox. “We are hand-in-glove, we are one team with the United States in this transition,” he said.
Still, some in Kyiv are worried that Trump’s desire for negotiations will play into the Russians’ hands. Ukrainian officials have said they believe Russia is trying to retake Kursk before Trump’s inauguration. If Kyiv can hold on to some territory in Kursk, it could give Ukraine a valuable bargaining chip in any peace talks.
“It’s the best Ukrainian forces against the best Russian forces,” said a 35-year-old Ukrainian sergeant fighting in Kursk who goes by the call sign Dzhyn. “At this rate, I see no reason for us to withdraw.”
Geniy, the battalion commander in Ukraine’s 47th Brigade, said that when his troops arrived in the Kursk region two months earlier, Russians were defending the area with only conscripted soldiers. Then about six weeks ago, the Russian counterattack began. Advancing in columns of armored vehicles, they forced the Ukrainians back from a small village in the area.
From a command post near the Russian border, which Wall Street Journal reporters visited last week, he watched a drone feed as three Russian soldiers crept through a forest toward a destroyed Ukrainian-held village in the Kursk region. Then, three more Russians appeared, not far away. Geniy called in a mortar strike, then another, then another. Each failed to hit them.
Dealing with three people isn’t that hard, but when it’s one after another after another, some of them are able to advance,” he said. “Sometimes it’s just a few meters, but over the course of weeks that becomes significant progress.”
Unlike on the eastern front—where Ukrainian troops have for months complained about shortages of ammunition and, especially, men—the brigades fighting in Kursk are mostly well-equipped. Using American-made Bradley Fighting Vehicles, Geniy said, his unit has been able to conduct regular troop rotations in the trenches, something the constant threat of drones has rendered nearly impossible for units without top-line equipment.
He said the long-range Western missiles changed the calculus in the region. Last week, Ukraine hit a command post with British-made Storm Shadow missiles, injuring a North Korean general, the Journal has reported.
Ukrainian officials say 10,000 North Korean troops have been deployed to the Kursk region, though no soldiers who talked to the Journal had encountered them in battle. Ukrainian troops have been given phrasebooks in Korean in case Kim Jong Un’s troops join the fray.
Geniy said the Russians have other advantages in Kursk: In the area where the 47th Brigade is fighting, Moscow has about three times as many men as the Ukrainians and six times as many small explosive drones used to attack vehicles and infantry.
Moscow’s losses in the Kursk offensive have been massive, according to Ukrainian troops fighting in different parts of the region. U.S. officials estimate that Russia is losing around 1,200 men dead and injured a day, across the entire front line. Since the start of the full-scale invasion of Ukraine, Moscow has sustained 700,000 casualties, according to British officials.
“It’s hard to count them—the field where they’re attacking is covered in bodies,” said one Ukrainian private fighting southeast of Sudzha, the main Ukrainian-held city in the Kursk region. “They’re literally stepping on the bodies of their comrades when they assault.”
But the losses don’t appear to be deterring the Kremlin, which is using Russia’s larger population to bleed Ukrainian forces. British officials have said they don’t believe Russian President Vladimir Putin wants to negotiate yet.
The soldier southeast of Sudzha said the Ukrainians were outnumbered roughly 10-to-1 in the area, and most soldiers in his battalion were injured and unable to fight.
Ukraine faces other challenges as well. Moscow is hammering supply lines and storage facilities with glide bombs, which Ukrainian forces have no way to shoot down. Basic communication is also difficult, because Starlink—Elon Musk’s satellite internet system, which has become an essential part of the Ukrainian military’s communications—doesn’t work inside Russian territory.
Vyachyslav Khomenko, a platoon commander with Ukraine’s 21st Mechanized Brigade, compared the fighting to Bakhmut, the deadliest battle of the war. Khomenko said his forces were outnumbered roughly 3-to-1 near the village of Pogrebki, which the Russians seized several weeks ago. He said his unit retreated beyond a dam, which will be difficult for Moscow to retake.
But in the third year of war, Khomenko said, motivating soldiers has become difficult. Roughly 90% of the troops in his platoon are conscripts with little experience or desire to fight.
“People are tired,” he said. “At least once a month, I have to remind them that they’re fighting so their grandkids won’t have to do this. The first year of the war, I wouldn’t have even thought of giving that kind of speech.”
Franz-Stefan Gady, a Vienna-based military analyst who recently visited Ukrainian military units, said Ukraine has struggled to replace casualties with new troops, leaving many units threadbare. The Russians, he said, appeared to be trying to wear down the Ukrainians before an even larger push to retake the Kursk region. He added that he didn’t think Putin was currently ready to negotiate, because he believed he was winning the war, but that could change if the U.S. was willing to increase arms deliveries to Ukraine as a lever to get Moscow to the bargaining table.
“The Ukrainian strategy there is to hold on to it as a bargaining chip and obtain a favorable attrition ratio vis-à-vis the Russians,” he said. He said he believed it would be hard for Ukraine to hold Kursk, but added, “I think the Russians will have a tough fight.”
Gen. Oleksandr Syrskiy, Ukraine’s top military commander, has told Ukrainian media that the Kursk operation has deterred Russian attacks elsewhere. Still, Moscow has advanced faster in eastern Ukraine over the past few months than at any point since the start of the full-scale war in 2022.
Ukrainian soldiers fighting in Kursk said it isn’t yet clear if the operation has been worth it. Some expressed anger at the territory lost in the east, where short-handed units were getting overrun. Others said that if they could hold on in Kursk until winter set in, it would be hard to oust them before spring.
Geniy, the battalion commander from the 47th Brigade, said he wasn’t sure how long they could hold Kursk.
“I think they’ll eventually push us back,” he said. “They add more power and more resources, and they have a goal to reach the border at any cost, so they will do it.”
Max Colchester and Aruna Viswanatha contributed to this article.
Write to Ian Lovett at ian.lovett@wsj.com