The Battle for Kupiansk
On December 2, 2025, Vladimir Putin announced the capture of Kupiansk in the Kharkiv region. In a swift countermove, Ukrainian forces commanded by Colonel Serhii Sydorin executed a successful operation that encircled the Russian troops. This maneuver stands as Ukraine's most significant military success since its army entered Russia's Kursk region in 2024. Fighters from the second 'Charter' Corps secured the Kupiansk city council building, marking a crucial strategic gain in the ongoing conflict. This development highlights the fluid and unpredictable nature of the front lines in eastern Ukraine.
Colonel Sydorin's Command
The operational group is led by 38-year-old Colonel Serhii Sydorin. Under his command, at least 1,500 Russian military personnel were killed or wounded, achieving a casualty ratio of ten Russians for every fallen Ukrainian soldier. By the operation's conclusion, only about 50 Russian troops remained in the vicinity of Kupiansk. Notably, Russian forces had utilized a disused gas pipeline for maneuvers behind Ukrainian lines until mid-September.
On September 21, Colonel Sydorin was given just three days to assemble a combat unit from elements of the second 'Charter' Corps. This newly formed unit faced a formidable Russian mechanized brigade and two motor rifle regiments.
Ukrainian assaults coincided with deteriorating weather, yet this did not hinder their offensive actions. Colonel Sydorin explained the strategy:
"We decided to conduct assault operations simultaneously in all directions. Not openly, but covertly. And where we achieved success, we developed it." — Serhii Sydorin
His units maintained constant forward movement, aiming to avoid large-scale engagements: 'If we detected the enemy, we primarily sought to destroy them using FPV drones, while the infantry advanced further to cut the enemy's logistical routes,' Sydorin added.
On October 29, Vladimir Putin invited Western journalists to visit Kupiansk, but the situation on the ground was already under Ukrainian control. The Institute for the Study of War (ISW) has confirmed the Ukrainian advances in Kupiansk, indicating significant shifts on the frontline and successes for Ukrainian forces against Russian units.
The Ukrainian recapture of Kupiansk represents a pivotal moment in the conflict, demonstrating the Armed Forces' capacity to execute effective counter-offensive operations under complex battlefield conditions. The success of Colonel Sydorin and his units may serve as a model for future Ukrainian army actions and could alter the balance of forces on the front, influencing the subsequent dynamics of combat in the region.