Russia likely lacks the reserves to properly defend itself if Ukraine breaks through a key defensive line, experts say

• Russia's forces appear to be stretched along its multi-layer defenses, a US think tank said.
• The same units appear to be deployed in both advanced and defensive roles, said the ISW.
• Russian forces are coming under significant pressure from Ukrainian attacks in Zaporizhzhia.

Russian defenses appear to lack strength in depth on a key part of the front line where Ukraine has recently made important gains, according to data from a US think tank.

The Institute for the Study of War said Tuesday that units from the same Russian divisions are deployed in Tokmak, a village just behind the front line which is a key target of Ukraine's counteroffensive, as well as in more advanced positions fighting Ukrainian forces.

This, the ISW said, suggests that Russia has not manned its multi-echeloned defense in southern Ukraine in depth.

"The deployment of the 70th and 71st Motorized Rifle Regiments as far back as Tokmak suggests that elements of the same Russian formations and units defending at forward positions are holding positions, likely in smaller numbers, in subsequent defensive layers," it said.

It added that it's possible that elements of other Russian units and formations hold rear defensive positions, but that the current Russian manpower commitment to holding positions on the frontline "indicates that this is unlikely."

Russian forces are coming under intense pressure from Ukrainian attacks in the southern Ukrainian Zaporizhzhia Oblast, with the ISW in other recent updates saying that Russian forces are stretched thin and elite units are sustaining high casualties during counterattacks.

Ukraine recently took control of the town of Robotyne, beyond Russia's initial defensive lines, and is targeting Tokmak, which lies on a strategically important road.

The ISW's assessment echoes that of other analysts, who say that Russian defenses beyond the initial, heavily fortified front two lines appear to be weak, suggesting that Ukraine could make rapid advances if it manages to break through.

Ukraine is probing Russian defenses at several points simultaneously along the heavily fortified "Surovikin line," in a bid to expose weak spots and force it to deploy elite units thinly, reports suggest.

One of the core aims of Russia's counteroffensive in south Ukraine is to retake the strategic town of Melitopol, which would enable it to significantly disrupt supplies traveling to the Russian-occupied Crimea peninsula by road and rail.