The hired mercenaries have encircled Ukraine's eastern city of Bakhmut, which has become a point of prestige for Kiev and Moscow.
Wagner, a Russian mercenary group, has advanced its offensive to take over the key town of Bakhmut in eastern Ukraine.
Russian artillery renewed attacks on the town on Tuesday, pushing through Ukrainian defences in a bid to besiege the town from all sides.
Many analysts say Wagner has put up its "last stand" against Ukrainian forces. One NATO official told CNN that the mercenary forces have lost five times more fighters in the city than their Ukrainian rivals.
Fighting on multiple fronts and the long-drawn-out battle in Bakhmut have led to fatigue in the Wagner ranks. The incessant fighting has caused so much devastation that the city of 70,000 has become a ghost town.
Ukraine’s President Volodymyr Zelenskyy on Monday ordered the Chief of Staff to send reinforcements to Bakhmut. Zelensky’s top adviser Mykhailo Podolyak stressed that Ukraine was fortifying its positions in the city with tens of thousands of military personnel ready to thwart a possible counterattack.
Russia-backed forces have been stationed at multiple points around Bakhmut but they are taking heavy casualties at the hands of Ukraine's defence forces. The situation has left Wagner chief Yevgeny Prigozhin frustrated as he has begun accusing Russian army of withholding weapons supply to his mercenaries and making them easy targets on the frontline.
READ MORE: Why is ‘meat grinder’ Bakhmut so crucial for Russia in Ukraine war
Rift between Russia and Wagner
Wagner mercenaries are being supported by local pro-Russia separatist forces in the Donbass region but the group is dependent on Moscow’s firepower.
As Prigozhin expressed disappointment over the Russian army not providing his hired guns with ammunition, backup firepower and reinforcement, the statement has rubbed staunch military loyalists in the wrong way.
"For now, we are trying to figure out the reason: is it just ordinary bureaucracy or a betrayal," Prigozhin said, noting that Wagner was yet to receive the necessary supplies and military back-up as promised by the Russian military leadership in February.
Igor Girkin, a former Federal Security Service (FSB) officer, who led Russian-backed forces in Donetsk region in 2014, lashed out at Prigozhin, accusing him of harbouring political ambitions that reflected his "psychopathy" and harmed the "common cause of victory over Ukraine."
Prigozhin had earlier said that his representatives were denied access to the headquarters of Russia's military in Moscow, a charge the Kremlin denies.
According to Wagner's chief between "12,000 and 20,000" Ukrainian troops are on the ground in Bakhmut to defend the city.
READ MORE: A battle of psychological value: Can Russia capture Ukraine’s Bakhmut?
The key to a deeper offensive or symbolic victory
Ukraine’s forces are digging trenches to fortify their defence and working to repair damaged roads for supplies and future soldier transfers to the city.
If Wagner mercenaries will truly capture the entire Bakhmut, it will be seen as a stepping stone for the further seizure of cities such as Kramatorsk and Sloviansk.
Russian Defence Minister Sergei Shoigu underlined on Tuesday that Bakhmut plays an important role to break Ukraine’s defence that would let Russia’s forces push deeper into the region.
"The city is an important hub for defending Ukrainian troops in the Donbass. Taking it under control will allow further offensive actions to be conducted deep into Ukraine's defensive lines," Shoigu said.
In an interview with CNN, President Zelenskyy said that the fall of Bakhmut will “open the door” for Russia to seize other Ukrainian cities.
“We understand that after Bakhmut they could go further. They could go to Kramatorsk, they could go to Sloviansk, it would be an open road for the Russians after Bakhmut to other towns in Ukraine, in the Donetsk direction," Zelenskyy said.
Not only a victory in Bakhmut against Ukraine’s forces will promote Wagner’s success in the field but also it will allow Prigozhin to have more influence in the Kremlin against Russian military bureaucracy.
A Russian victory in Bakhmut also means Moscow will make its first territorial gain since last summer.