Russian forces have made fresh tactical advances into Kostiantynivka, the Institute for the Study of War (ISW) assessed on 10 June. The city sits at the southern tip of Ukraine's Donetsk Oblast Fortress Belt — Moscow's main effort for the spring-summer 2026 offensive. Russia missed its own May deadline to take the city, and the wider fortified chain stays out of operational reach.
Two named Russian formations have pushed into eastern Kostiantynivka from the south, Ukrainian military observer Kostiantyn Mashovets reported on 10 June. He identified them as the "Bakhmut" tactical group and the "Dzerzhinsk" (Toretsk) tactical group. The "Bakhmut" group is built around Russia's 3rd Army Corps (AC) under the Southern Grouping of Forces. The "Dzerzhinsk" group operates in the area of responsibility of the 8th Combined Arms Army (CAA) of the Southern Military District. It likely includes elements of five CAAs, the 3rd AC, and Russian naval fleets, Mashovets noted.
Elements of the "Bakhmut" group pushed from Stupochky through Novodmytrivka into northeastern Kostiantynivka. They also advanced along the T-0504 Pokrovsk-Bakhmut road as far as the city's railway station. The "Dzerzhinsk" group moved from Illinivka, south of the city, into areas stretching from northwestern to southwestern Kostiantynivka near the railway station. Mashovets assessed that it has likely achieved a tactical breakthrough in the western, central part of the city. Forward assault elements of the two groups now stand roughly two kilometers apart. Russian forces have so far failed to seize the railway station. Ukrainian troops cleared the village of Dovha Blaka southwest of the city of Russian infiltrators.
ISW noted that Russian forces opened the campaign for Kostiantynivka in August 2025 after seizing the majority of Chasiv Yar and Toretsk, with Toretsk alone running to roughly 26,000 Russian casualties. The first Russian troops infiltrated Kostiantynivka itself in October 2025. Russia has since worked into at least 12.69% of the city. Ukrainian officials reported earlier this spring that the Russian command had set a May 2026 deadline for the seizure. That deadline has come and gone.
Russia has poured forces into the effort regardless. Ukrainian Commander-in-Chief Oleksandr Syrskyi said on 2 May that Russian activity in this direction noticeably increased in April. Russian units in the area had reportedly been replenished by 80% as of 6 June, ISW noted. The Russian command reportedly redeployed elements of the 70th Motorized Rifle Division to the Kostiantynivka-Chasiv Yar area last December. The redeployment likely came in preparation for the spring push.
ISW assessed that Russian forces will likely keep infiltrating throughout Kostiantynivka. They will likely consolidate positions in parts of the city while suffering high casualties. Russia's 3rd AC northeast of the city appears to be struggling to dislodge Ukrainian forces from Chasiv Yar. That inhibits any move to envelop Kostiantynivka from the north. A Russian milblogger claimed on 9 June that Ukrainian forces recently counterattacked near Chasiv Yar. The milblogger added that Ukraine still holds Podilske and Mykolaivka west of the town.
The northern flank of the Fortress Belt is also bogged down. Russia opened its spring-summer 2026 offensive with mechanized assaults around Lyman. Those assaults signaled intent to advance on Sloviansk from the northeast. They produced no significant gains, ISW noted. The Russian command likely shifted weight south to Kostiantynivka. Russia's Western Grouping of Forces covers the front from Kupiansk through Lyman. It likely lacks the combat power to push on Sloviansk while balancing operations toward Kupiansk and Borova.
Key developments on June 9:
Ukraine has approved a long-term concept for the development of its rocket forces and artillery, outlining plans to build up capabilities through 2030, Commander-in-Chief Oleksandr Syrskyi said.
Syrskyi said the concept defines the main directions for modernization while Ukraine continues fighting a full-scale war, stressing that long-term force development must run in parallel with current battlefield needs.
He said Ukrainian artillery units are already conducting thousands of fire missions daily and inflicting significant losses on Russian forces, supported by a mix of domestically developed systems and weapons supplied by international partners.
According to Syrskyi, Ukraine operates one of the most diverse ranges of artillery systems globally and uses nearly all available types of ammunition, gaining continuous combat experience against a numerically superior adversary.
Syrskyi said Russia’s invasion has significantly changed the character of modern warfare, with growing use of drones, guided bombs, and other precision strike systems reshaping battlefield dynamics.
He said artillery remains a core component of the battlefield despite evolving technology, but its effectiveness now depends heavily on reconnaissance quality and the speed of information transfer.
At the same time, he pointed to several challenges affecting Ukraine’s rocket and artillery forces, including dependence on foreign ammunition supplies, complex logistics linked to multiple systems, limited range in some platforms, and shortages in artillery reconnaissance capabilities.
The concept foresees a gradual transition toward Ukrainian-made artillery systems as the backbone of future force structure, while aging Soviet-era systems that cannot be upgraded will be phased out.
Ukraine will also retain units equipped with modern foreign systems and streamline its overall artillery inventory to improve efficiency and logistics.
Syrskyi said a key priority is the creation of a modern artillery reconnaissance system to improve targeting speed and battlefield coordination.
A separate priority is the expansion of Ukraine’s missile forces to increase deep-strike capability across operational and strategic depth.
Syrskyi said this includes completing development and scaling production of domestic ballistic and cruise missiles, which – together with unmanned systems – would form a layered long-range strike capability with a reach of up to 2,000 kilometers.
He said artillery will remain a decisive element of battlefield effectiveness and a central factor in deterring further Russian aggression, regardless of terrain or conditions.
Key developments on June 8:
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