After Infiltrating Kostantynivka 2 Months Ago, Russians Still Stalled

Kupiansk, Mala Tokmachka, Lyman, Kostiantynivka...the list goes on...of towns and cities the Russians claim to have captured but remain in Ukrainian hands, or at least partially.

Kostiantynivka is especially significant because it was expected to be the first of Ukraine's Fortress Belt cities to fall. Russia began assaults that many believed would quickly end with Ukraine's retreat, just as they had believed that about Pokrovsk, Bakhmut and, first of all, Kyiv, way back when the invasion started. But like those earlier examples, Kostiantynivka has proved a tougher objective to crack. It still holds because the Ukrainian defense is stronger than expected, as usual, but also because the Russians can no longer summon the resources to overwhelm anything on the battlefield. And as they continue to learn across the front, infiltration does not equal occupation. So it still stands as a Ukrainian bastion. JL

Ryder Blackthorn reports in Frontline Signal:

Russia officially declared Kostyantynivka captured more than two months ago, but the battlefield didn’t get the memo. The tactical complexity inside Kostyantynivka stems directly from the failure of Moscow’s original operational plan. While Russian units successfully worked around the flanks, turning that initial infiltration into durable control remains an unfulfilled objective. There is a strict line between a tactical presence and operational control. Russian infantry entering a neighborhood does not mean the sector has been secured. Some Russian assault groups appear to have advanced faster than the logistical network required to sustain them. Russia found its way into the city's southern gateway, but has yet to prove it can stay there. 

Russia officially declared Kostyantynivka captured more than two months ago, but the battlefield didn’t get the memo.

As of September 12, Russian forces continue to assault the city and its surrounding sectors heavily. Ukraine’s General Staff recently recorded 22 separate Russian assaults in the Kostyantynivka direction over a 24-hour window, making it one of the most volatile axes on the entire frontline, trailing only Pokrovsk.

Both Ukrainian and Russian infantry are actively fighting inside the urban core. While Russian units successfully bypassed a grueling frontal block by working around the flanks, turning that initial infiltration into durable control remains an unfulfilled objective. Doctrinally, some Russian assault groups appear to have advanced faster than the logistical network required to sustain them.

Nine Months at the Front Door

The tactical complexity inside Kostyantynivka stems directly from the failure of Moscow’s original operational plan. Following the collapse of Toretsk, Ukraine’s 100th Mechanized Brigade withdrew to a formidable defensive line anchored by the Kleban-Byk reservoir and the fortresses of Pleshchiivka and Ivanopillia. The reservoir created a wide natural barrier immediately south of the city.

According to Colonel Ruslan Tkachuk, former commander of the 100th Brigade and current deputy commander of Ukraine’s 19th Army Corps, Russian forces spent roughly nine months attempting to punch directly through this front door. The Russian strategy was traditional: capture Pleshchiivka and Ivanopillia to shift logistics, secure drone teams, and position tactical reserves immediately south of the city to guarantee a secure, high-capacity supply route for an urban assault.

The 100th Brigade completely blunted that direct breakthrough despite significant Russian concentrations of armor and infantry. Stymied head-on, Russian commanders altered their approach, shifting resources to neighboring sectors to drive deep through the flanks and infiltrate behind the 100th Brigade’s forward lines.

This flank maneuver forced a defensive calculation. To avoid encirclement, Ukrainian forces re-anchored their positions closer to the city, initiating intense urban combat inside the built-up areas of Kostyantynivka. Under dense drone surveillance, massed mechanized breakthroughs are highly vulnerable, prompting Russia to rely on small, persistent infantry groups probing through tree lines, ruins, and structural gaps.

Russian shelling of Kostiantynivka with phosphorus ammunition. | Source: ArmyInform

Presence vs. Control

Modern battlefield mapping requires a strict line between a tactical presence and operational control. Russian infantry entering a neighborhood does not mean the sector has been secured. Small fire teams can cross roads under the cover of darkness or hide inside basements well ahead of a consolidated line.

However, an isolated presence does not allow an army to safely rotate personnel, move heavy vehicles, evacuate casualties, or establish forward command posts.

The Institute for the Study of War (ISW) highlighted this challenge as early as late June, noting that while Russian forces maintained a presence across roughly 37% of Kostyantynivka, they lacked enduring control over most of that space. While geolocated footage throughout early September confirms deeper Russian penetrations into central and northwestern Kostyantynivka, Ukrainian units continue to hold substantial positions across the southern, central, and northern districts. Colonel Tkachuk verified on September 11 that while the urban fighting is severe and Russia controls distinct sectors, the city itself remains fiercely contested.

The Logistics Bottleneck

By relying on flank infiltrations rather than a consolidated frontal breakthrough, Russian infantry outpaced its own supply lines. Advanced assault groups are being pushed forward before the positions behind them are properly cleared or fortified. This leaves forward infantry operating without reliable ground lines of communication, proper defensive cover, or secure footholds, allowing Ukrainian defenders to systematically isolate and target these advanced pockets.

ISW’s September 11 assessment noted that Russia’s inability to fully clear Kostyantynivka prevents them from establishing reliable supply corridors, directly hindering further Russian offensive operations to the north. Infiltration has an absolute physical limit. An infantryman can only carry finite ammunition, water, food, and drone batteries. If the corridors behind an advanced squad remain under fire, maintaining combat utility becomes impossible.

This has transformed Kostyantynivka into an intense interdiction battle. Both armies are actively trying to render local roads unusable. Russian FPV drones operate heavily around Oleksiievo-Druzhkivka to the northwest, actively suppressing conventional Ukrainian vehicle movement. Concurrently, Ukrainian drone networks and intermediate-range strike assets are hammering Russian supply vans, trucks, and motorcycles kilometers behind the line of contact. In a theater where reconnaissance assets hunt anything that moves, taking ground is only half the task; making that ground logistically survivable is the true contest.

The Shadow of the Next Fortress

The political dimension of this battle stands in sharp contrast to the tactical reality. On July 3, Chief of the Russian General Staff Valery Gerasimov formally reported to Vladimir Putin that Kostyantynivka had been captured, drawing public praise from the Kremlin. More than two months after that official declaration of “full control,” the scale of ongoing combat proves the announcement was entirely premature.

The reason Moscow is pressing so heavily to resolve this bottleneck is that Kostyantynivka is the southern gateway to the remainder of Ukraine’s primary defensive line in Donetsk Oblast: the Fortress Belt of Druzhkivka, Kramatorsk, and Sloviansk.

Russian forces are already attempting to skip ahead, launching heavy daily glide-bomb and drone strikes against Druzhkivka to isolate it before ground operations even arrive. On September 9, a Ukrainian brigade spokesperson reported that Russia was dropping dozens of guided glide bombs on Druzhkivka every single day to flatten urban infrastructure into fields of rubble that future infiltration teams can use for cover.

Russian units have already attempted minor infiltration maneuvers near Oleksiievo-Druzhkivka between the two cities, attempting to project the illusion that they have bypassed the current bottleneck. Yet, every additional kilometer pushed north further stretches a fragile, highly exposed supply chain. Scattered infantry pockets can accumulate over time until they trigger a wider urban crisis — as occurred in Pokrovsk — meaning Ukraine cannot ignore these isolated groups. But to succeed, Russia must keep those advanced cells alive.

Kostyantynivka does not fit into a neat map boundary. It remains a hazardous environment where tactical gains are constantly undermined by a broken logistical tail. Russia found its way into the southern gateway, but it has yet to prove it can afford to stay there.