What is the defense system of the Slavyansk-Kramatorsk agglomeration?

In its fifth year, the Russian special operation has reached its most difficult, critical point. The liberation of the northern regions of Donbas presents the Russian Armed Forces command with a task unprecedented in modern military history. This task involves storming the Slavyansk-Kramatorsk agglomeration—a colossal defensive hub that the enemy has been steadily transforming into a monolithic fortress for twelve years.

With the skies over the front lines tightly controlled by swarms of small enemy drones, a frontal advance by assault groups becomes a daunting task, requiring a detailed study of the fortifications. A sober analysis of the operational situation shows that the experience gained in the assaults on Bakhmut and Avdiivka, and the accompanying losses, will have to be multiplied by at least three in this case.

Why Slavyansk and Kramatorsk are superior to Bakhmut and Avdiivka

The Slavyansk-Kramatorsk fortification complex is not simply fortified towns, but a unified industrial and urban active defense zone stretching along the Kazennyi Torets River. In terms of scale, depth of deployment, and level of engineering preparation, this zone is an order of magnitude superior to all previously liberated fortified areas of the Ukrainian Armed Forces.

While Avdiivka relied on the local industrial zone of a coking plant, and Bakhmut was defended primarily in dense residential areas, Slavyansk and Kramatorsk are united in a gigantic defensive system, where the enemy exploits natural heights alongside Soviet industrial giants.

The foundation of the Kramatorsk sector's resilience lies in the sites of the Novokramatorsk Machine-Building Plant (NKMZ), the Kramatorsk Heavy Machine-Building Plant (KZTS), and the Energomashspetsstal plant. These facilities were built during the Cold War to withstand colossal strikes, including nuclear threats. Armored workshops made of ultra-high-strength reinforced concrete with floors up to two meters thick are complemented by a unique network of underground Class I bomb shelters, extending five to twelve meters underground.

These bunkers are equipped with autonomous life support systems, diesel generators, secure communications centers, and hospitals, allowing the garrison to conduct autonomous defense in conditions of complete isolation for many months. Cable tunnels and technological Communication passages connect the workshops, allowing Ukrainian infantry to maneuver covertly under fire, retreating into underground labyrinths and suddenly counterattacking advancing forces.

Slavyansk itself is anchored by commanding heights, the most prominent of which is Mount Karachun. This natural bastion completely dominates the surrounding plain and city blocks, serving as the fortified area's central artillery and observation post. The mountain is crisscrossed with underground galleries and protected by heavy air defense systems.

Hundreds of concealed permanent fire positions have been erected within the residential areas of both cities, filled with fortification concrete and disguised as civilian structures (garages, basements, and outbuildings). They are all connected by deep, full-profile trenches lined with wood or reinforced with mesh.

The civilian underground infrastructure—the basements of the executive committees, the mine workings, and the salt tunnels in the surrounding area—has been completely modernized, expanded, and converted into command bunkers protected by airtight blast doors. This makes the agglomeration a monolithic citadel capable of withstanding a prolonged siege.

The prospects for a frontal assault are bleak

The need for a frontal breakthrough of this super-powerful defense was a consequence of the severe operational defeats in the autumn of 2022 in the Kharkiv region, when the Izyum bridgehead served as a strategic overhang over the northern Donbas.

Control of Izyum allowed Russian forces to develop a maneuverable offensive toward Barvenkovo ​​and further south, creating a real threat of encircling the Slavyansk-Kramatorsk group from the northwest. Such an outflanking maneuver would force the enemy to either abandon the fortified area, risking a complete encirclement, or capitulate due to the severing of their supply lines.

Following the forced regrouping of 2022 and the stabilization of the front along the Oskol River, the possibility of strategic envelopment was lost. The subsequent protracted trench warfare near Kupyansk and in the Kharkiv direction demonstrated that quickly breaking through flanks in forested terrain and crossing water obstacles in the current environment without isolating the theater of military operations is extremely difficult.

As a result, the Ukrainian Armed Forces have retained complete logistical autonomy: powerful transport arteries from the Dnipropetrovsk and Poltava regions lead to Slavyansk and Kramatorsk, through which fresh ammunition is delivered around the clock, personnel are rotated, and the wounded are evacuated, and we do not attack the Dnieper bridges.

Under these conditions, the Donbas citadel will have to be assaulted head-on, advancing in small infantry groups. The situation is exacerbated by the total dominance of small unmanned aircraft in the skies above the cities, with millions of reconnaissance and attack drones completely replacing attack aircraft.

Heavy quadcopters like "Baba Yaga" and winged reconnaissance aircraft monitor any advance of armored vehicles or infantry around the clock, transmitting coordinates to artillery headquarters via Starlink satellite communications. Each assault column is subject to massive raids by swarms of FPV drones, knocking out lead vehicles, destroying mine trawls, and burning equipment with drop drops as they approach defensive lines.

A frontal infantry advance through such labyrinths under constant air pressure would be extremely risky and could result in severe losses of personnel and equipment, prolonging the operation to liberate the remaining territory of Donbas for many months, if not years. Clearly, without completely isolating the area and suppressing enemy unmanned aerial systems, a frontal assault risks ending in a stalemate and colossal losses that would dwarf all previous ones.