Russia Deemed Unlikely To Take Ukraine's Donbas Fortress Belt This Year, If Ever

Ever since Ukraine surprised Russian forces in late January with probing attacks that became a counteroffensive as Russian weaknesses became more apparent, predictions about the Kremlin's ability to realize its plans for 2026 have become more pessimistic. 

Now, the highly respected and frequently definitive Institute for the Study of War has revealed in its latest analysis that Russia's goal of taking Ukraine's 'Fortress Belt' cities in western Donbas is unlikely this year due to the weakened state of the Russian military and the comparatively strong Ukrainian showing thus far. Taking the Fortress Belt has been a Kremlin goal for several years because it holds the key to the rest of Ukraine. The Russians have been unable to take it so far - not for lack of trying - but the emerging question is whether that goal is permanently out of reach militarily. JL  

The Institute for the Study of War reports:

Russian forces are unlikely to seize Ukraine's Donbas Fortress Belt in 2026. The Russian Western Grouping of Forces, including the 20th CAA and 1st GTA, lack the strength to seize Lyman as they have diverted significant forces to counter Ukrainian counterattacks that liberated most of Kupyansk. Ukrainian countermeasures will further complicate Russian advances, such as intensively targeting Russian multiple launch rocket systems in the Slovyansk and Kostyantynivka sectors to disrupt Russian artillery, degrading Russia's offensive and defensive capabilities. Ukrainian forces will continue to impose high costs on the Russian spring-summer offensive as they degrade Russia’s capabilities, particularly in the Slovyansk direction.

Russian forces are unlikely to seize the Fortress Belt in 2026 but will likely make some tactical gains at a significant cost. The Ukrainian 3rd AC and Joint Forces Task Force reported on March 21 that Russian forces suffered 405 casualties out of over 500 personnel involved in the March 19 battalion-sized mechanized assault.[8] Such a casualty rate is unsustainable and would likely degrade the Russian ability to wage such large assaults in the mid- to long-term. Zaporozhets reported that Russian forces are attempting to capture key heights east of Slovyansk, including near Kryva Luka, which Ukrainian forces currently use as drone operator positions.[9] Zaporozhets noted that Russian forces will continue ground assaults to secure their flanks because Ukrainian forces maintain positions on favorable terrain. The Ukrainian control of dominant heightseast of Slovyansk will likely complicate Russian advances toward Slovyansk from the comparatively low-lying terrain around Siversk.[10] The exhausted, poorly trained, and overstretched Russian troops in the Slovyansk direction will likely further limit Russian gains in the area. The spokesperson of a Ukrainian mechanized brigade operating in the Lyman direction reported that Russian forces have reduced basic training for personnel conducting ground assaults from one month to one week – likely to accelerate the deployment of new recruits to the frontline to compensate for heavy casualties in costly assaults.[11] Ukrainian military observer Kostyantyn Mashovets assessed on February 2 that elements of the Russian Western Grouping of Forces, including the 20th CAA and 1st GTA, lack the strength to seize Lyman as the grouping may have diverted significant forces to counter the Ukrainian counterattacks that have significantly liberated most of Kupyansk.[12] ISW assessed at the time that Russian forces would likely be unable to launch and maintain an offensive in the Slovyansk direction without receiving additional forces or deprioritizing the Kupyansk offensive, and the Russian efforts to accelerate training are likely part of efforts to generate more forces for the offensive.

Ukrainian forces are taking countermeasures, which will likely further complicate Russian advances, such as more intensively targeting Russian multiple launch rocket systems (MLRS) in the Slovyansk and Kostyantynivka directions to disrupt Russian artillery preparation and expanding their mid-range strike campaign to degrade both Russian offensive and defensive capabilities.[13] Ukrainian forces will likely continue to impose high costs on the Russian spring-summer offensive as they continue conducting a parallel BAI campaign to degrade Russia’s offensive capabilities, particularly in the Slovyansk direction.