Russian forces were decimated on a key part of the front line, losing more than 300 troops in one day: ISW

• Russian forces are suffering steep losses in the western Zaporizhia Oblast in Ukraine.
• Russian units lost more than 300 troops in one day, a US think tank said, citing a Ukrainian official.

Russian forces suffered steep casualties on a key part of the front line in Ukraine, losing more than 300 troops in one day, according to a US think tank.

The Institute for the Study of War, a US-based think tank that provides daily updates on the conflict, said that Russia is likely struggling to find "combat-effective" units in the face of mounting losses in the western Zaporizhia Oblast, one of the key points of Ukraine's counteroffensive.

Citing Ukrainian military spokesman Colonel Oleksandr Shtupun, it said Russia suffered 313 casualties near the village of Tavariisk on Monday, where ferocious fighting has raged in recent weeks.

It's an increase on the 200 casualties Russian forces in the area suffered in each of the previous two days, said Shtupen.

After weeks of grueling fighting as part of their counteroffensive to drive back Russia from territory it occupies in south and east Ukraine, Ukrainian forces in late August achieved a significant success: they broke through Russia's first line of defense and took control of the village of Robotyne.

It brought them one step closer to breaching Russia's formidable defensive lines and advancing on the strategically vital town of Melitopol, a Russian logistics hub.

Insider was unable to independently verify the casualty figures cited by the ISW, but the think tank said it had previously assessed that elite Russian airborne, or VDV, units appeared to have been significantly "degraded" in launching counterattacks against Ukrainian forces in Robotyne.

It said so-called "storm V units" of Russian convict recruits had been sent to the region, presumably to act as "cover" should elite units need to retreat.

"'Storm-Z' detachments are often combat ineffective and will likely provide the Russian defense in western Zaporizhia Oblast with marginal combat power," it noted.

The report echoes claims by British military intelligence, which in a tweet on Monday said that VDV paratroopers were being deployed to Robotyne, that the units were significantly under strength, and that their deployment signalled that Russian ground forces in the region were over-stretched.

"Throughout the war, Russian commanders have attempted to regenerate the airborne forces as a highly mobile, striking force for offensive operations. Once again, they are being used as line infantry to augment over-stretched ground forces," it said.

Ukraine is believed by analysts to be preparing for an attack on the town of Tokmak, which sits on a road to the strategically vital town of Melitopol. The core aim of Ukraine's southern counteroffensive is to sever Russia's land bridge to the occupied Crimea peninsula by seizing Melitopol.