Russian infighting may have led to Ukraine retaking a key town in its counteroffensive: report

• A Russian mercenary group refused to fight in Ukraine, reports say. 
• It may have enabled Ukraine to seize back control of the village of Robotyne. 
• Infighting has racked the Russian military in recent weeks. 

A Russian mercenary group's decision to stop fighting in protest at the Kremlin's lack of action to save their leader may have helped Ukraine achieve an important breakthrough on the front line. 

Ukraine on Sunday said its forces had liberated the village of Robotyne, which is on a network of roads leading to Melitopol, the occupied south Ukrainian city.