The Underground Warfare Defining Eastern Ukraine’s Battlefields – Eight Ukrainian soldiers sent into a trench near Pokrovsk were out of action within 24 hours. The next four lasted less than 10 minutes.
A few hundred yards away, six men hidden in two fighting holes held out for 10 days.
Switchblade Drone. Image Credit: Industry Handout.
French volunteer Édouard Maurin, who served with a Ukrainian special-purpose battalion in 2024 and 2025, described the two positions this week in the War on the Rocks. The first, an 80-meter-long open trench codenamed HOMAR, was already known to Russian forces and exposed from above. The second, CRAB, was dug into a tree line, camouflaged, and supplied by drone.
A total of 12 men were knocked out of the fight at HOMAR in just over 24 hours. At CRAB, six men vanished from Russian sight and carried on fighting.
From there, the six Ukrainian soldiers helped direct artillery and drone strikes against advancing Russian troops.
‘Being Seen Kills’
Maurin’s lesson from the fighting was simple: on parts of the Ukrainian front, “being seen kills faster than being outgunned.”
The fighting around Kotlyne, west of Pokrovsk, shows how drones are changing the physical shape of the war.
Maurin said he thought the contested area was about one kilometer deep at the start of last year. It is now five to eight times wider. The distinction between Russian- and Ukrainian-held ground is less precise in many places, with the disputed zone stretching as deep as 12 kilometers.
Troops Hiding in Russian-Held Areas
Small groups of Ukrainian soldiers can remain hidden inside territory that most war monitors consider to be Russian-held.
Maurin calls it “residual presence”: soldiers do not necessarily have to occupy a conventional defensive line visibly, as long as they can “access, observe, communicate, and act” within contested territory.
Former Google CEO Eric Schmidt returned from Ukraine this summer describing much the same battlefield.
“Movement above ground has become almost suicidal,” Schmidt wrote in The Washington Post on September 9.
Throughout the visit, Schmidt said he saw Ukrainian commanders working from deep underground while unmanned vehicles carried out vital reconnaissance, transferred supplies and attacked Russian positions above them. Ukrainian commanders reported that some troops had been forced to stay underground for months as traveling between positions left them exposed to drone attacks.
The ‘Death Zone’
That danger has produced a remarkable return to underground warfare. Writing for the Modern War Institute last month, John Spencer and Col. Drew Craig said soldiers had described an approximately 30-kilometer “death zone” in some parts of the front. These are places in which above-ground movement can quickly attract an attack.
AI-assisted targeting and other technological advances are making it increasingly awkward to discreetly transport men or equipment. Fiber-optic FPV drones cannot even be jammed in the same way as radio-controlled drones.
Both armies have responded with more than just deeper foxholes. Vast networks of subterranean command posts, drone workshops, logistics routes, and ammunition stores are functioning. Some Ukrainian positions now use reinforced concrete, ventilation, fiber-optic communications, and concealed passages between various positions.
Kyiv Has Built Subterranean Hospitals
Ukraine has also constructed underground hospitals close to the front lines.
“Centralized infrastructure is increasingly vulnerable on transparent battlefields,” the pair outlined.
Russia Is Tunneling to Ukrainian Positions
Russian forces are routinely utilizing pipelines and other underground routes to subtly seek out Ukrainian positions. During fighting in Russia’s Kursk region last March, Russian troops moved within sections of the disused Urengoy-Pomary-Uzhhorod gas pipeline.
Is Russia Threatening Kyiv’s Edge?
Much of Ukraine’s staying power in this conflict has been enabled not only by its public’s overwhelming opposition to the Russian invasion, but by its rapid technological advancements. Russia may have a much larger population than Ukraine, and therefore more human capital to funnel into its armed forces, but Kyiv’s tactics and technology have changed faster than Moscow’s. In August, Ukraine said that its method of targeting critical Russian energy and infrastructure sites via its rapid drone and missile barrages had inflicted a £35 billion hit to Russia’s war chest.
Schmidt has warned, however, that the gap between Ukraine’s technological edge and Russia’s capabilities is narrowing, and that “Russia is shifting its strategy to erase Kyiv’s battlefield advantages.”
A May 2025 CSIS study described Ukraine’s new ground strategy as: “disaggregate to survive, reaggregate when necessary.”
About the Author: Georgia Gilholy
Georgia Gilholy is a journalist based in the United Kingdom who has been published in Newsweek, The Times of Israel, and the Spectator. Gilholy writes about international politics, culture, and education.
