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.