Ukraine's Defense Forces advanced more than 15 km through underground utility tunnels into Russia's rear on the Kupiansk axis in Kharkiv Oblast, the Khartiia Corps of Ukraine's National Guard reported on 22 October. The corps called it Operation Veles. The underground advance was paired with attacks on the surface and drone strikes, hitting Russian forces from two directions, the corps told Militarnyi.

Russian troops have repeatedly crawled through gas pipelines around Kupiansk to get behind Ukrainian lines, even after Ukraine reported confident control of the city in February. This time, Ukraine went underground itself. The operation took away Russia's chance to get into Kupiansk's rear, the corps said.

The corps reported more than 30 Russian soldiers captured and Russian losses of more than 100. Militarnyi, citing the unit, put the number of Russian troops killed at over 100.

Khartiia studied how Russian troops moved through pipes before going underground itself, the corps commander, Brigadier General Ihor Obolenskyi, said.

"We watched how the enemy works underground and studied how they do it. The Russians intended to use gas pipelines to get into the rear of our troops. So we went underground ourselves. We anticipated the enemy's actions and mastered the tactics of underground combat," he said.

Boots under ground!

Asymmetric breakthrough in the Kharkiv Region: Khartiia Corps conducts the subterranean counteroffensive Operation VELES, advancing 15 km underground.

Corps Commander General Ihor Obolenskyi explains a unique operation. pic.twitter.com/qRQ93kckpK

— Khartiia Corps in English (@khartiia_eng) October 22, 2026

For the operation, troops trained physically and psychologically to fight in confined spaces, sappers and engineers prepared the underground route, and special communications, navigation, silent logistics, and life-support systems were put in place, Khartiia told Militarnyi. The operation was named after Veles, the Slavic pagan god of the underworld.

Khartiia's brigade, the R.U.H. assault regiment, the Lava drone regiment, the Achilles drone brigade, and units of Ukraine's military intelligence, including the Freedom of Russia Legion and the Russian Volunteer Corps, took part, the corps said.

Russia has used pipelines to infiltrate before

By September 2025, Russian forces had used pipelines to move troops behind Ukrainian lines three times, Ukrainian monitoring project DeepState reported on 12 September 2025. The first was in Avdiivka, the second near Sudzha, and the third near Kupiansk, where groups crossed the Oskil River through a gas pipe.

Near Sudzha in March 2025, Russian special forces walked through a pipeline that until recently had carried Russian gas to Europe, the Associated Press reported. A pro-Kremlin blogger claimed they covered about 15 km and that some spent several days inside.

Russian troops kept using the pipeline near Kupiansk this year. On 27 September, Khartiia's reconnaissance drones recorded Russian forces leading nine civilians, including children, elderly people, and a person on crutches, through the gas pipeline out of the Kupiansk community. Men of military age in civilian clothes walked alongside them, and the corps believes they were Russian soldiers using the group as cover to withdraw. Ukrainian troops held fire because of the civilians, the corps said, adding that the case has been documented for a war crimes investigation.

Why the war is moving underground

Drones, constant surveillance, and AI-assisted targeting have made the battlefield surface transparent and deadly, argue John Spencer, chair of urban warfare studies at West Point's Modern War Institute, and Col. Drew Craig, principal military engineering staff officer at NATO's Allied Rapid Reaction Corps. In an August analysis, they write that soldiers in Ukraine describe a "death zone" of some 30 km, where moving above ground can draw an attack within minutes. When firepower makes the surface too dangerous, armies have historically gone underground, as they did in World War I and Vietnam, and more recently in Gaza and Lebanon.

"Armies that cannot survive above ground must adapt below it," the authors write.

Fighting in tunnels brings its own requirements, the authors write: detecting the enemy by sound and vibration, and specialized unmanned systems that cannot rely on GPS or stable radio links. Long stretches underground also take a severe psychological and physical toll on soldiers.

Western militaries are not ready for this, Spencer and Craig write. No NATO partner maintains even general capabilities for large-scale underground warfare, and US and British efforts focused mainly on detecting and clearing tunnels rather than occupying and operating in them.

Editor's note: Most of the Ukrainian soldiers and commanders interviewed are identified by their callsigns, in accordance with military protocols.

KHARKIV OBLAST — Ukrainian soldier Oleksandr had already narrowly survived crossing a mine-strewn field and a river in the crosshairs of Russian artillery when the swarm of first-person-view

According to HUR's Active Operations Department, the operation was carried out by its Group 10 special forces unit, which reportedly thwarted Russian offensive plans and prevented Russian troops from cutting off Ukrainian logistical routes in the region.

"The trend this year continues," Zelensky said, "Since the start of fall, our warriors have liberated more territory than the Russians have managed to capture. The same was true at other points this year."

Ukrainian infantry encircled and retook the village of Kolodiazi north of Lyman without getting drawn into street fighting, while a drone battalion kept the sky above them shut, the battalion’s chief of staff told Suspilne on 18 October. The village fell during the fourth and final phase of Operation Vivaldi, Ukraine’s counteroffensive in northern Donetsk Oblast.

For years now, Russia has aimed to seize Lyman and cross the Siverskyi Donets River. It needs this area to encircle Ukraine’s fortress belt of Donetsk Oblast cities from the northwest, ISW assesses. Vivaldi’s four phases retook 277 km² and 16 settlements on that approach, and a veteran of the operation has said Ukraine’s assault troops suffered more than ten times fewer casualties than Russian forces doing it.

Drones over the infantry

The 60th Mechanized Brigade fought in all four phases of Vivaldi and took Kolodiazi in the last one, said the chief of staff of the brigade’s Fatum unmanned systems battalion, callsign Krash.

“Our task, as an unmanned systems battalion, was to escort and ‘close’ the air in front of our infantry to make it impossible for the enemy to hit it. To suppress all the firing assets possible,” he said.

The brigade’s 3rd Mechanized Battalion, the main striking force, encircled Kolodiazi and retook it without getting drawn into street fighting, Krash said. The 1st Mechanized Battalion kept Russian reinforcements out of the area, while drone crews suppressed artillery, hit supply runs, and worked against Russian drone operators.

500 troops and 200-plus vehicles

The drone battalion killed or wounded about 500 Russian troops during the fourth phase and struck Russian armored vehicles, trucks, and motorbikes, its chief of staff said.

“More than two hundred pieces of various equipment: Grad and Uragan multiple rocket launchers, various armored vehicles, tanks, armored combat vehicles. Most of all motorbikes and quad bikes, there the count runs into the hundreds. This is our enemy’s main logistics tool,” he said.

Ghost villages

The villages retaken in northern Donetsk Oblast are nearly empty of civilians, Krash said.

“It’s very typical for de-occupied settlements: these are ghost towns. You can see right away where the occupier stepped. All the settlements are under the control of the Third Army Corps, our forces stand there and prevent enemy infiltration. But civilian life in these towns is either absent or very scarce,” he said.

Third Army Corps commander Brigadier General Andrii Biletskyi reported Kolodiazi’s liberation, along with Zelena Dolyna and Lypove, when he summed up Vivaldi’s fourth phase, which secured 101 km².

Ukrainian forces are advancing east of Sloviansk and Kramatorsk, and even Russian milbloggers now acknowledge it, the Institute for the Study of War (ISW) said on 8 October. The gains may follow months of groundwork like the one that preceded Operation Vivaldi near Lyman, which Ukraine says returned 176 km² to its control. Russian commentators are already doubting that Moscow can reach the two cities.

Russia's years-long push on the Fortress Belt, the chain of cities anchoring Ukraine's defense in Donetsk Oblast, has been stalling since Vivaldi began. Unable to take those cities, Russia keeps hitting them from the air. On 8 October, a Russian bomb killed 30 people on two buses in Kramatorsk.

Across the Siverskyi Donets

Russian milbloggers said Ukrainian forces liberated Ozerne and advanced east of Pyskunivka toward Kryva Luka, ISW reported. They also acknowledged that Ukrainian troops drove Russian forces out of Pyskunivka. Ukrainians are now counterattacking toward Kryva Luka from the west and northwest, from across the river.

ISW called the repeated Russian claims of a river crossing notable, because the Siverskyi Donets is a significant natural obstacle. Kryva Luka is a dominant height just south of the river. From there, Ukraine could launch further counterattacks. Ukrainian forces appear to have pushed Russian troops off both banks in this area, ISW assessed.

The heights Russia wanted

After Vivaldi cleared ground near Lyman in September, Russia shifted its push south toward Mykolaivka and Sloviansk. Russian forces likely see Mykolaivka, just east of Sloviansk, as a primary objective, ISW said. Its heights would favor an offensive on the city. Ukrainian pushes northeast and southeast of the town now deny Russia that terrain.

East of Kramatorsk, milbloggers claimed Ukrainians liberated Malynivka and advanced between Fedorivka Druha and Holubivka. They also reported gains into southern Minkivka and near Fedorivka. The lines remain tangled. Geolocated footage shows Ukrainian forces striking a Russian position in central Tykhonivka after what ISW assesses was a Russian infiltration.

ISW said the counterattacks may point to a broader Ukrainian goal: pushing Russian forces east, away from the Sloviansk–Kramatorsk area and toward the Siverskyi Donets–Donbas Canal.

The Vivaldi playbook

The counterattacks have run for weeks. On 29 September, Ukrainian military observer Kostiantyn Mashovets reported them in the same areas, saying Russia's 3rd Combined Arms Army had failed to make significant gains. ISW assesses that the attacks build on months of shaping meant to wear down Russia's offensive capacity.

Before Vivaldi, Ukrainian forces targeted Russian drone operators, gaining drone superiority before the counteroffensive. They used the same approach ahead of their Oleksandrivka counterattacks in early 2026.

Moscow appears to see the pattern. A Ukrainian military official said on 7 October that Russia is moving drone units and Spetsnaz from quieter sectors to the Sloviansk–Kramatorsk direction. Ukraine also reorganized its command in and around Donetsk Oblast in early September, which may be blunting Russian attacks from the east, ISW said.

"Distant" and "doomed"

One Russian milblogger called an advance toward the Sloviansk–Kramatorsk area a "distant" prospect, ISW reported. A Russian offensive from Siversk toward Sloviansk may be "doomed" to failure or heavy losses unless Russia retakes the forests south of Lyman, he said.

The counterattacks east of the two cities appear to support Vivaldi, ISW assessed. Together with Russia's defeat north of the river, they could disrupt Russia's offensive toward Sloviansk from the east entirely.

If Ukraine holds Kryva Luka and keeps Russia off the Mykolaivka heights, Moscow's pincer on Sloviansk and Kramatorsk loses the ground it was built on.

"Skipper", an FPV company commander in Ukraine's 413th Raid Unmanned Systems Regiment, has described destroying a Russian UR-77 mine-clearing vehicle with drones during the 2023 counteroffensive as the strike he is proudest of, according to Army TV.

The UR-77, nicknamed "Zmiy Horynych" after a fire-breathing serpent of Slavic folklore, carries a rocket-fired line charge to blow paths through minefields, as per Militarnyi. Each charge carries more than two tons of explosives, which is why a cheap FPV hit can trigger a blast far larger than the drone itself.

"It exploded so hard that I thought it was a small nuclear blast. There are more than two tons of plastic explosive inside, and when it went off after the second hit, it was something unbelievable," Skipper says.

Skipper joined the army at the start of the full-scale invasion and moved from infantry and aerial reconnaissance to commanding an FPV unit. His regiment now operates on the Zaporizhzhia front, where FPV drones conduct combat missions.

From sailing yachts to FPV drones

In civilian life, Skipper was a sailing instructor, and he says the sport partly helps in military work, especially his knowledge of navigation and radio communication. He is convinced that a technological edge can be one of the keys to victory.

He counts the UR-77 strike among his unit's early work, from a time when few Ukrainian units were using FPV drones at all, he says. The hit came during hard fighting in the counteroffensive, when his crews were among the first to work the FPV niche.

Russia turns a mine-clearer into a wrecking tool

The UR-77 was built in the 1970s for a different war, one of fast tank thrusts that needed enemy minefields cleared quickly. Its base rides on the chassis of the 2S1 Gvozdika self-propelled howitzer, and its charge can cut a lane six meters wide, with some anti-personnel mines detonated across a band up to 15 meters wide.

Modern combat changed that role. The classic mine-clearing use remains, but Russia now more often turns these machines on Ukrainian fortifications, using the line charge to flatten defenses rather than open a path.