Executive Summary
- Battlefield assessment. The front lines remained largely stable despite an intensifying Russian ballistic missile campaign, while Ukraine reported improved interception rates against jet-powered drones.
- Ukraine’s subterranean warfare campaign. Ukraine is now taking the offensive underground near Kupiansk, contesting pipelines used for Russian infiltration across the Oskil River.
- What to monitor. Russia’s new Filin cruise missile could place additional pressure on Ukrainian air defenses if produced at scale.
1. Battlefield Assessment
Last week’s fighting brought little change to the battlefield geometry and a slightly lower operational tempo. For most of the week, daily tactical engagements remained below 200, a deviation from a months-long trend toward more frequent combat. Pokrovsk once again bore the brunt of the fighting.
With Kyiv facing a dwindling stock of interceptors, Russian forces launched more ballistic missile salvos against Ukrainian population centers. Ukraine’s Main Directorate of Intelligence (GUR) estimates that the Russian military has no shortage of ballistic and cruise missiles, as well as drones, for its air raids. Russia continues to produce missiles using Chinese machine tools and dual-use components and subcomponents from Western sources.
The Ukrainian General Staff reported an improving interception rate, at times up to 80 percent, against Russian jet-powered drones. A growing number of battlefield visuals vindicate Kyiv’s claims of higher interception rates against these weapons. However, larger datasets collected over several months will be needed to draw firm conclusions.
2. Ukraine’s Subterranean Operation Gains Ground
The most important development in last week’s fighting was Ukraine’s Veles campaign, the most notable tunnel warfare effort of the ongoing conflict. Beneath the Kupiansk front, Ukrainian and Russian troops have been fighting inside gas pipelines barely four feet in diameter. These narrow passages offer concealment from drones observing combat formations from above, but leave combatants little room to move, engage the enemy, or evacuate the wounded. The tactical engagement is placing unusual demands on both Ukraine’s and Russia’s militaries.
Ukraine’s Operation Veles has brought this subterranean contest into focus. The operation combines combat inside pipelines with surface operations designed to disrupt a Russian infiltration route beneath the Oskil River. Since summer 2025, Russian forces have used the Shebelynka–Ostrohozk gas pipeline to reach the river’s Ukraine-controlled western bank. The underground corridor lets Russian infantry penetrate the wooded areas north of Kupiansk and enter the city while reducing exposure to Ukrainian surveillance and fire. Ukraine’s subterranean campaign, conducted by the Ukrainian 2nd Khartiia Corps alongside other combat formations, aims to close a persistent vulnerability in the country’s defenses.
Closing the corridor through which Russian forces have entered Kupiansk has required Ukraine to do more than attack its entrances. Russian troops have reportedly bypassed damaged sections of the pipeline, cut new openings, and resumed movement through the ducts. As a result, Ukrainian forces have repeatedly found themselves tasked with intercepting Russian forces before they enter the underground route or engaging them after they emerge.
Operation Veles seeks to end this vulnerability by allowing Ukraine to establish control inside the passage itself. Visuals from the combat operations show Ukrainian forces working with a high degree of coordination. Sappers, engineers, mini unmanned ground vehicles, and elite combat troops are working continuously to seize the subterranean offensive edge.
This fighting has placed exceptional demands on Ukrainian assault units. Troops have advanced through confined spaces where firefights could occur at close range. Soldiers from the 425th Separate Assault Regiment, Skelia, have participated alongside other formations.
Ukrainian accounts describe drones monitoring Russian personnel at distances as short as approximately 65 feet. Ukrainian social-media posts have further detailed the construction of sandbag barricades, the installation of machine guns, and the demolition of selected pipeline sections. The collective effort has also required Ukrainian units to maintain underground ventilation and sustain communications with command-and-control hubs and follow-on troops as they fight their way into Russian lines. They have coordinated this underground advance with surface maneuver and drone strikes.
Operation Veles's central objective is to deny Russian combat formations a concealed route across the Oskil River and limit their ability to sustain infiltration into Kupiansk. According to official Ukrainian statements, forces participating in the operation have advanced more than nine miles through underground infrastructure. Last week Ukrainian President Volodymyr Zelenskyy reported that more than 100 Russian personnel had been eliminated in the campaign, and over 30 captured, though these figures have not been independently verified.
The operation has also revealed the broader military utility of underground infrastructure. Beyond infiltration, protected subterranean passages can support resupply, casualty evacuation, and troop rotation efforts. Maintaining these functions, however, requires ventilation, reliable communications, secure access points, and sustained engineering work. Without such support, a route that conceals movement from aerial observation can quickly become a confined, hazardous environment with few escape options.
Subterranean warfare has a long history. But modern surveillance and precision strike capabilities are renewing its importance. Drones make it increasingly difficult for land forces to assemble, move supplies, or approach defensive positions without detection. Tunnels, utility networks, and pipelines offer these forces opportunities to preserve concealment and complicate enemy targeting.
The value of such underground structures is especially pronounced in urban warfare and on static battlefield geometries, where familiar infrastructure can be adapted for sustained military use. For modern forces like Russia’s and Ukraine’s, this creates a need to understand and contest the battlefield below ground alongside the surface and the airspace above. Success in a subterranean environment depends upon engineers, specialized reconnaissance teams, communications, and coordination among troops operating in different physical environments. Moreover, control of a narrow underground passage can influence infiltration, logistics, and the security of positions across a much larger area.
3. What to Monitor in the Coming Weeks
Russia’s new Filin cruise missile could bring a dangerous new dimension to Moscow’s long-range strike deterrent. The missile is a ground-launched weapon with a reported range of roughly 760 miles, and can fly at very low altitudes while carrying a 110- or 220-pound warhead. According to Ukrainian intelligence, the missile combines 3D-printed parts, Chinese-made inertial navigation equipment, and electronics common to other Russian weapons.
The missile’s significance lies in its potential for mass production. If the Russian defense technological and industrial base can manufacture the Filin inexpensively and in substantial numbers, it could expand Moscow’s strike capacity and, alongside existing missile and drone attacks, further strain Ukraine’s beleaguered air defenses. To assess whether Moscow is mass-producing the Filin in the coming weeks, look for larger and more frequent combined salvos, strikes against Ukraine’s energy infrastructure, and evidence that the missile is accurate and resistant to electronic warfare. Wreckage and production data will also help establish whether the Filin is becoming a reliable, scalable weapon—or whether its advertised capabilities exceed its battlefield performance.