Ukraine’s Security Service (SBU) detained two men suspected of scouting targets for Russian strikes on Sloviansk and Dnipro, the agency reported on 14 October. Catching both early let it secure Ukrainian reserve command posts and the gas stations the alleged agents had been hunting, the agency added.

Sloviansk anchors the northern end of the Fortress Belt, the chain of fortified cities that has held Ukraine’s defense of Donetsk Oblast since 2014. Russia is pushing to seize them, and its aircraft bombed a residential area of Sloviansk on 11 October. Where Ukrainian convoys stop and troops gather is exactly what Russian handlers allegedly asked these suspects to supply.

A gas station worker suspected of filming convoys

The first suspect worked at a gas station complex in Sloviansk, Donetsk Oblast. Russian intelligence allegedly reached him through a former classmate who left for Russia after the full-scale invasion and now works for its special services, the SBU said. He then allegedly used his phone to secretly film Ukrainian army convoys at or near gas stations. He was allegedly supposed to send the photos and videos to Russia to help it prepare a targeted strike. He also allegedly drove his own car around other gas stations and bridges that the Defense Forces use for logistics.

Spotted through Telegram comments

The second suspect, a former Pokrovsk resident, moved to Dnipro in 2024 and settled in a dormitory. Russian intelligence noticed him through pro-Kremlin comments he posted in Telegram chats, investigators say. A female handler in Russia allegedly tasked him with guiding missile and drone attacks on places in the city where Ukrainian troops and equipment were concentrated. He allegedly scouted on foot or took public transport to reach outlying districts.

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Officers seized computers and smartphones containing evidence of the men’s alleged work for Russia. Both are suspected of treason under martial law and of unauthorized dissemination of information on Ukrainian troop movements or deployment, under Articles 111(2) and 114-2(2) of the Criminal Code. They remain in custody without bail and face up to life imprisonment with confiscation of property. The SBU’s office for Donetsk and Luhansk oblasts ran the operation under the Donetsk Oblast Prosecutor’s Office.

Ukrainian forces are advancing east of Sloviansk and Kramatorsk, and even Russian milbloggers now acknowledge it, the Institute for the Study of War (ISW) said on 8 October. The gains may follow months of groundwork like the one that preceded Operation Vivaldi near Lyman, which Ukraine says returned 176 km² to its control. Russian commentators are already doubting that Moscow can reach the two cities.

Russia's years-long push on the Fortress Belt, the chain of cities anchoring Ukraine's defense in Donetsk Oblast, has been stalling since Vivaldi began. Unable to take those cities, Russia keeps hitting them from the air. On 8 October, a Russian bomb killed 30 people on two buses in Kramatorsk.

Across the Siverskyi Donets

Russian milbloggers said Ukrainian forces liberated Ozerne and advanced east of Pyskunivka toward Kryva Luka, ISW reported. They also acknowledged that Ukrainian troops drove Russian forces out of Pyskunivka. Ukrainians are now counterattacking toward Kryva Luka from the west and northwest, from across the river.

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ISW called the repeated Russian claims of a river crossing notable, because the Siverskyi Donets is a significant natural obstacle. Kryva Luka is a dominant height just south of the river. From there, Ukraine could launch further counterattacks. Ukrainian forces appear to have pushed Russian troops off both banks in this area, ISW assessed.

The heights Russia wanted

After Vivaldi cleared ground near Lyman in September, Russia shifted its push south toward Mykolaivka and Sloviansk. Russian forces likely see Mykolaivka, just east of Sloviansk, as a primary objective, ISW said. Its heights would favor an offensive on the city. Ukrainian pushes northeast and southeast of the town now deny Russia that terrain.

East of Kramatorsk, milbloggers claimed Ukrainians liberated Malynivka and advanced between Fedorivka Druha and Holubivka. They also reported gains into southern Minkivka and near Fedorivka. The lines remain tangled. Geolocated footage shows Ukrainian forces striking a Russian position in central Tykhonivka after what ISW assesses was a Russian infiltration.

ISW said the counterattacks may point to a broader Ukrainian goal: pushing Russian forces east, away from the Sloviansk–Kramatorsk area and toward the Siverskyi Donets–Donbas Canal.

The Vivaldi playbook

The counterattacks have run for weeks. On 29 September, Ukrainian military observer Kostiantyn Mashovets reported them in the same areas, saying Russia's 3rd Combined Arms Army had failed to make significant gains. ISW assesses that the attacks build on months of shaping meant to wear down Russia's offensive capacity.

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Before Vivaldi, Ukrainian forces targeted Russian drone operators, gaining drone superiority before the counteroffensive. They used the same approach ahead of their Oleksandrivka counterattacks in early 2026.

Moscow appears to see the pattern. A Ukrainian military official said on 7 October that Russia is moving drone units and Spetsnaz from quieter sectors to the Sloviansk–Kramatorsk direction. Ukraine also reorganized its command in and around Donetsk Oblast in early September, which may be blunting Russian attacks from the east, ISW said.

"Distant" and "doomed"

One Russian milblogger called an advance toward the Sloviansk–Kramatorsk area a "distant" prospect, ISW reported. A Russian offensive from Siversk toward Sloviansk may be "doomed" to failure or heavy losses unless Russia retakes the forests south of Lyman, he said.

The counterattacks east of the two cities appear to support Vivaldi, ISW assessed. Together with Russia's defeat north of the river, they could disrupt Russia's offensive toward Sloviansk from the east entirely.

If Ukraine holds Kryva Luka and keeps Russia off the Mykolaivka heights, Moscow's pincer on Sloviansk and Kramatorsk loses the ground it was built on.

Russia lost almost 300 km² of Ukrainian territory on net between March and September 2026, and it likely gained no ground in September despite its heaviest casualties of the year, the Institute for the Study of War (ISW) assessed. Ukraine's Operation Vivaldi accounts for much of the swing. The think tank notes that Ukraine's secrecy around such counterattacks makes exact monthly tallies hard.

Russia has pressed attacks along the entire front through 2026, accepting mass casualties for marginal ground, and its battlefield year has already been called its worst since 2023. Its losses have been outpacing its recruitment for months.

Russia came out behind in September

Russian forces seized 175.54 km² in September but lost 256.35 km², a net loss of 80.81 km², or minus 2.69 km² a day, ISW calculated. The balance stayed negative when Russian infiltrations into areas Russia does not control are counted: Russia seized or infiltrated 143.2 km² but lost 318.38 km², a net loss of 175.18 km².

The September figures include at least 147 km² near Lyman that Ukraine liberated over earlier months, but that ISW recorded only once details of Operation Vivaldi emerged in September. The operation already disrupted Russia's plan to encircle the Fortress Belt cities from the Lyman and Dobropillia directions.

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Almost 300 km² lost since March

Russia's rate of seizing territory dropped sharply in March 2026 and has stayed low, or even negative, since, ISW found. After controlling for the gains Ukraine made during Vivaldi, Russia lost control of 293.59 km² net across the front since March. Counting infiltrations, it gained a presence in only 174.44 km² over the same period.

ISW's monthly chart shows net Russian losses of 116.01 km² in April and 281.1 km² in May, modest gains in June, July, and August, and a net loss again in September. Oleksandr Syrskyi, then Ukraine's commander-in-chief, reported in June that Ukrainian forces had recaptured 100 km² in May.

More than 46,000 casualties for no ground

Russian forces suffered 46,230 casualties in September, Ukraine's General Staff reported. It is the third straight month above 40,000 and the highest monthly toll of 2026, by Kyiv's count. Monthly Russian casualties have climbed from 32,980 in April to 42,860 in July and 42,020 in August, ISW's chart shows.

Russia keeps suffering heavy personnel losses while making extremely limited or even net-negative territorial gains, ISW said, and its current force generation system still recruits fewer soldiers than it needs to replace them.

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Ukraine's effective operational security around Vivaldi, likely to continue in future counterattacks, will make meaningful month-to-month assessments of Russian gains and losses hard, the think tank added.

The Institute for the Study of War (ISW) published a map in its analytical report on 24 September that contrasts the claimed Russian encirclement with the location of Russian forces as assessed by the experts. Based on the evidence observed by ISW, the nearest area where Russian forces are present is 10.2 kilometers from the southeastern outskirts of Dobropillia.

Russia has been spreading disinformation about its successes around Dobropillia as part of what ISW calls a cognitive warfare effort to portray Ukrainian defenses as on the verge of collapse. Russia's Defense Ministry published a map claiming the city was surrounded. ISW's own map challenges it. The Ukrainian military says the city remains under its control.

Russian Defense Ministry claims it is already destroying encircled Ukrainian troops in Dobropillia and moving further

Units of Russia's Center Grouping of Forces continue combat operations against encircled Ukrainian forces in the Dobropillia area of Donetsk Oblast while simultaneously advancing toward Oleksandrivka, the Russian Defense Ministry claimed. ISW analysts, meanwhile, said they have not observed evidence supporting Russia's claim that the city is encircled. They also noted that Ukrainian officials "directly refute" the claim.

ISW observed evidence that Russian infiltrators, small groups, were operating east and northeast of Dobropillia on 19 and 20 September. The institute did not assess that these infiltrators had consolidated their positions.

Ukrainian forces maintain positions south and northeast of Dobropillia, military observer Kostiantyn Mashovets said on 20 September, according to ISW.

Russian forces have not made major gains in the Dobropillia direction, the chief of staff of an artillery reconnaissance battalion said on 22 September, according to the institute. On the same day, a Russian milblogger described the "alleged Russian encirclement of Dobropillia" as potentially meaning not the direct presence of infantry, but only the establishment of fire control over Ukrainian logistics, including roads west of Dobropillia and toward Sviatohorivka, according to ISW.

ISW noted that Russia's pervasive military culture of lying—what Russian milbloggers themselves call "beautiful reports"—has degraded the Defense Ministry's own ability to understand the battlefield and enabled inflated claims like the Dobropillia encirclement.

Russia uses this disinformation as a "diversion"

In its statement, the Russian Defense Ministry itself described Dobropillia as a "strongly fortified settlement" whose seizure would threaten key Ukrainian supply lines running from Dnipropetrovsk Oblast toward the Fortress Belt—the Sloviansk-Kramatorsk-Druzhkivka urban agglomeration.

Russia has recently renewed its attempts to break through toward Dobropillia.

Third Army Corps Commander Andrii Biletskyi said that Russian forces sought to bypass the fortified cities through Dobropillia and link up with troops advancing from north of Lyman, rather than launch a direct assault. ISW noted on 16 September that the Vivaldi operation disrupted Russia's two-pronged plan. In its 24 September report, ISW said Russia's claims about Dobropillia were partly intended to divert attention from Ukraine's elimination of the Russian salient north of Lyman, which has likely forced Russia's command to rethink its wider encirclement plans.

Russia’s Defense Ministry claimed on 22 September 2026 that it had surrounded Dobropillia, but the Institute for the Study of War (ISW) found no evidence to support the announcement. Dobropillia is a small town in Donetsk Oblast, known as the "pearl of the Donbas" for its coal industry, which has helped make Ukraine's Fortress Belt cities, holding the region from Russians since 2014, per RBC Ukraine.

Ukraine’s Vivaldi counteroffensive in Donetsk Oblast broke the northern arm of Russia’s plan to surround the fortified cities. ISW says Moscow’s Dobropillia claim diverts attention from that setback and portrays Ukrainian defenses as collapsing during the 81st session of the UN General Assembly, held on 21-28 September. The institute says Russia is likely spreading such claims to support its push for Ukraine’s capitulation.

Meanwhile, Ukrainian officers say Russian assault groups are still trying to break through toward Dobropillia, but have made no major gains.

Russia’s encirclement claim clashes with Ukrainian battlefield reports

Russia’s Ministry of Defense has claimed its troops were advancing toward Oleksandrivka, a village northwest of Dobropillia, but published no map to support its account.

At the same time, Ukrainian military observer Kostyantyn Mashovets said Ukrainian troops still held positions south and northeast of the city, which the experts said was inconsistent with the claimed encirclement.

ISW reported that a Ukrainian artillery reconnaissance battalion chief of staff said on 22 September that Russia had made no major advances near Dobropillia. He said Russian commanders kept postponing deadlines because of heavy losses and a gap between their plans and battlefield conditions.

A Ukrainian battalion officer said Russian troops were still trying to slip through Ukrainian lines in small groups.

How Dobropillia fits Russia’s plan to surround the fortress belt

Dobropillia is a transport hub on the southwestern approach to Ukraine’s “fortress belt,” which includes Kostiantynivka, Druzhkivka, Kramatorsk, and Sloviansk. These cities have anchored Ukraine’s defense in Donetsk Oblast since 2022.

Ukraine’s Third Army Corps commander, Andrii Biletskyi, whose corps is conducting the Vivaldi counteroffensive north of Lyman, explained that Russian forces advancing through Dobropillia were meant to join another force coming from north of Lyman, behind the fortified cities, encircling them rather than attacking them head-on.

ISW had already assessed on 16 September that Vivaldi had made the two-sided plan infeasible. In its 22 September report, ISW said Russia’s false claim about Dobropillia partly aims to divert attention from those Ukrainian gains.

Russian assaults toward Dobropillia continue

The setback north of Lyman has not stopped Russia’s push toward Dobropillia. Ukrainian staff sergeant Dmytro Davydenko reported on 14 September a sharp increase in assault groups moving toward the city, sometimes more than his unit could engage. He said Ukrainian troops had mined, blocked, or destroyed the main approaches.

ISW reported that Russia was preparing armor and drone support for possible assaults using armored vehicles this fall. A Ukrainian battalion officer said fog might help Russia move that equipment, although Ukrainian reconnaissance and drones would make it difficult. He said Russian glide bombs continued to strike infrastructure in the area.